Medical device operational modes

ABSTRACT

An ambulatory medical device comprising: a monitoring component comprising at least one sensing electrode for detecting a cardiac condition of a patient; at least one processor configured for: adjusting one or more detection parameters for detecting the cardiac condition of the patient based at least in part on at least one of 1) one or more environmental conditions and 2) input received from the monitoring component; and providing at least one of an alarm and a treatment in response to detecting the cardiac condition of the patient based on the adjusted one or more detection parameters.

CLAIM OF PRIORITY

This application claims priority under 35 USC § 119(e) to U.S. PatentApplication Ser. No. 62/235,165, filed on Sep. 30, 2015, the entirecontents of which are hereby incorporated by reference.

BACKGROUND

This disclosure relates to systems and techniques for changingoperational parameters and modes of a medical device.

There are a wide variety of electronic and mechanical devices formonitoring and treating patients' medical conditions. In some examples,depending on the underlying medical condition being monitored ortreated, medical devices such as cardiac pacemakers or defibrillatorsmay be surgically implanted or connected externally to the patient. Insome cases, physicians may use medical devices alone or in combinationwith drug therapies to treat patient medical conditions.

One of the most deadly cardiac arrhythmias is ventricular fibrillation,which occurs when normal, regular electrical impulses are replaced byirregular and rapid impulses, causing the heart muscle to stop normalcontractions and to begin to quiver. Normal blood flow ceases, and organdamage or death can result in minutes if normal heart contractions arenot restored. Because the victim has no perceptible warning of theimpending fibrillation, death often occurs before the necessary medicalassistance can arrive. Other cardiac arrhythmias can include excessivelyslow heart rates known as bradycardia.

Implantable or external pacemakers and defibrillators (such as automatedexternal defibrillators or AEDs) have significantly improved the abilityto treat these otherwise life-threatening conditions. Such devicesoperate by applying corrective electrical pulses directly to thepatient's heart. For example, bradycardia can be corrected through theuse of an implanted or external pacemaker device. Ventricularfibrillation can be treated by an implanted or external defibrillator.

For example, certain medical devices operate by substantiallycontinuously monitoring the patient's heart through one or more sensingelectrodes for treatable arrhythmias and, when such is detected, thedevice applies corrective electrical pulses directly to the heartthrough one or more therapy electrodes.

SUMMARY

In one aspect, an ambulatory medical device includes a monitoringcomponent that includes at least one sensing electrode for detecting acardiac condition of a patient. The ambulatory medical device alsoincludes at least one processor. The at least one processor isconfigured for adjusting one or more detection parameters for detectingthe cardiac condition of the patient based at least in part on at leastone of 1) one or more environmental conditions and 2) input receivedfrom the monitoring component. The at least one processor is alsoconfigured for providing at least one of an alarm and a treatment inresponse to detecting the cardiac condition of the patient based on theadjusted one or more detection parameters.

Implementations can include one or more of the following features.

In some implementations, the adjusting includes dynamically adjustingthe detection parameters for detecting the cardiac condition.

In some implementations, the ambulatory medical device includes asensor. The at least one processor is configured to sense the one ormore environmental conditions based on input from the sensor.

In some implementations, the sensor includes a moisture sensor.

In some implementations, the sensor includes a motion sensor.

In some implementations, the sensor includes a pressure sensor. The atleast one processor is configured to monitor a patient sleep while thepatient is asleep. The pressure sensor detects a pressure indicative ofthe patient sitting or lying down.

In some implementations, the one or more environmental conditionsinclude a location of the ambulatory medical device.

In some implementations, the ambulatory medical device includes alocation module configured to determine the location of the ambulatorymedical device.

In some implementations, the location module is one of a GPS module, anNFC module, a Bluetooth® module, and a WLAN module.

In some implementations, the ambulatory medical device includes an audiointerface configured to receive and provide audible information.

In some implementations, the at least one processor is configured toadjust the operational parameters based at least in part on the receivedaudible information.

In some implementations, the audio interface is configured to interactwith an audio system that receives, provides, or receives and providesthe audible information.

In some implementations, the ambulatory medical device includes at leastone therapy electrode in communication with the at least one processor.

In some implementations, the at least one therapy electrode isconfigured to deliver defibrillation current.

In some implementations, the at least one therapy electrode isconfigured to deliver one or more pacing pulses.

In some implementations, the at least one processor is configured fordetecting that the cardiac condition may be occurring. The detecting isbased at least in part on 1) input received from the monitoringcomponent and 2) one or more detection parameters that correspond to theadjusted detection parameters. The at least one processor is alsoconfigured for selecting a treatment sequence corresponding to thecardiac condition.

In some implementations, the monitoring component is configured tomonitor one or more patient parameters. The one or more patientparameters include one or more of a heart rate, a respiration rate, ablood pressure, and one or more occurrences of pre-ventricle contraction(PVC).

In some implementations, the one or more adjusted detection parametersinclude a lower sensitivity level for detecting the cardiac conditionthan a sensitivity level of the detection parameters prior to theadjusting.

In some implementations, the one or more adjusted detection parametersinclude a higher sensitivity level for detecting the cardiac conditionthan a sensitivity level of the detection parameters prior to theadjusting.

In some implementations, the sensitivity level is based at least in parton motion detected by a motion sensor of the ambulatory medical device.

In some implementations, the sensitivity level is inversely proportionalto an intensity of the motion detected by the motion sensor.

In some implementations, the cardiac condition is an arrhythmiacondition.

In another aspect, an ambulatory medical device includes a monitoringcomponent that includes at least one sensing electrode for detecting acardiac condition of a patient. The ambulatory medical device alsoincludes at least one processor configured for adjusting one or moretreatment parameters for treating the cardiac condition of the patientbased at least in part on one or more environmental conditions. The atleast one processor is also configured for providing at least one of analarm and a treatment in response to detecting the cardiac condition ofthe patient based on the adjusted one or more treatment parameters.

Implementations can include one or more of the following features.

In some implementations, the cardiac condition is an arrhythmiacondition.

In some implementations, the ambulatory medical device includes awearable medical device.

In some implementations, the ambulatory medical device includes agarment configured to be worn about a torso of the patient.

In another aspect, an ambulatory medical device includes a monitoringcomponent that includes at least one sensing electrode for detecting acardiac condition of a patient. The ambulatory medical device alsoincludes at least one processor configured for selecting an operatingmode of the ambulatory medical device based at least in part on at leastone of 1) one or more environmental conditions and 2) input receivedfrom the monitoring component. The mode corresponds to a state of thepatient monitored by the ambulatory medical device.

Implementations can include one or more of the following features.

In some implementations, the operating mode is selected based on aninput received via a user interface of the ambulatory medical device.

In some implementations, the ambulatory medical device includes asensor. The at least one processor is configured to detect the one ormore environmental conditions based on input from the sensor.

In some implementations, the sensor includes a moisture sensor. The atleast one processor is configured to select a water operating mode ifthe moisture sensor detects a moisture content that meets or exceeds athreshold.

In some implementations, the sensor includes a motion sensor. The atleast one processor is configured to select an activity operating modeif the motion sensor detects a motion indicative of the patient being inan active state.

In some implementations, the sensor includes a pressure sensor. The atleast one processor is configured to select a patient sleep operatingmode if the pressure sensor detects a pressure indicative of the patientsitting or lying down.

In some implementations, the one or more environmental conditionsinclude a location of the ambulatory medical device.

In some implementations, the ambulatory medical device includes alocation module configured to determine the location of the ambulatorymedical device.

In some implementations, the location module is one of a GPS module, anNFC module, a Bluetooth® module, and a WLAN module.

In some implementations, the ambulatory medical device includes an audiointerface configured to receive and provide audible information.

In some implementations, the at least one processor is configured toselect the operating mode based at least in part on the received audibleinformation.

In some implementations, the audio interface is configured to interactwith an audio system that receives, provides, or receives and providesthe audible information.

In some implementations, the audio system is a car audio system.

In some implementations, the at least one processor is configured toselect the operating mode based at least in part on 1) the one or moreenvironmental conditions and 2) the input received from the monitoringcomponent.

In some implementations, the ambulatory medical device includes at leastone therapy electrode in communication with the at least one processor.

In some implementations, the at least one therapy electrode isconfigured to deliver defibrillation current.

In some implementations, the at least one therapy electrode isconfigured to deliver one or more pacing pulses.

In some implementations, the at least one processor is configured fordetecting that the cardiac condition may be occurring. The detecting isbased at least in part on 1) input received from the monitoringcomponent and 2) one or more detection parameters that correspond to theselected operating mode. The at least one processor is also configuredfor selecting a treatment sequence corresponding to the cardiaccondition. The treatment sequence is associated with the selectedoperating mode.

In some implementations, the one or more detection parameters include anextended amount of time in which the at least one processor detects thatthe cardiac condition may be occurring that is longer than an amount oftime in a default operating mode.

In some implementations, the one or more detection parameters include areduced amount of time in which the at least one processor detects thatthe cardiac condition may be occurring that is shorter than an amount oftime in a default operating mode.

In some implementations, the monitoring component is configured tomonitor one or more patient parameters. The one or more patientparameters include one or more of a heart rate, a respiration rate, ablood pressure, and one or more occurrences of pre-ventricle contraction(PVC).

In some implementations, a motor vehicle operating mode is among themodes from which the at least one processor is configured to select.

In some implementations, the at least one processor is configured forproviding an indication that the patient should refrain from operating amotor vehicle based at least in part on one or more of the patientparameters monitored by the monitoring component.

In some implementations, the one or more detection parameters include alower sensitivity level for detecting the cardiac condition than asensitivity level in a default operating mode.

In some implementations, the one or more detection parameters include ahigher sensitivity level for detecting the cardiac condition than asensitivity level in a default operating mode.

In some implementations, the higher sensitivity level is based at leastin part on motion detected by a motion sensor of the ambulatory medicaldevice.

In some implementations, the higher sensitivity level is inverselyproportional to an intensity of the motion detected by the motionsensor.

In some implementations, the selected treatment sequence includes anextended amount of time in which a response is expected from the patientthat is longer than an amount of time in a default operating mode.

In some implementations, the at least one processor is configured forcarrying out the treatment sequence. The treatment sequence includescausing at least one therapy electrode to deliver a therapy to thepatient.

In some implementations, the treatment sequence includes providing anindication that the therapy is about to be delivered to the patient.

In some implementations, the indication is an audible alarm. A volume ofthe alarm is based on the selected operating mode.

In some implementations, the at least one processor is configured to,before causing the at least one therapy electrode to deliver the therapyand after causing the indication that the therapy is about to bedelivered to be provided, allow the patient to provide an input thatcauses the ambulatory medical device to refrain from delivering thetherapy to the patient.

In some implementations, the cardiac condition is an arrhythmiacondition.

In some implementations, selecting an operating mode includes selectinga motor vehicle operating mode.

In another aspect, an ambulatory medical device includes a monitoringcomponent that includes at least one sensing electrode for detecting acardiac condition of a patient. The ambulatory medical device alsoincludes at least one processor configured for receiving an indicationthat the patient is in a wet environment. The at least one processor isalso configured for selecting an operating mode of the ambulatorymedical device based at least in part on the indication that the patientis in the wet environment.

Implementations can include one or more of the following features.

In some implementations, the operating mode is selected based on aninput received by a user interface of the ambulatory medical device.

In some implementations, receiving an indication that the patient is ina wet environment includes detecting that a moisture level meets orexceeds a threshold.

In some implementations, the moisture level is detected by a moisturesensor of the ambulatory medical device.

Implementations can include one or more of the following advantages.

In some implementations, the patient can use the ambulatory medicaldevice in multiple environments (e.g., while showering/bathing, whilesleeping/sitting, while exercising, etc.) without compromising theefficacy of the ambulatory medical device's monitoring and/or treatmentcapabilities. Parameters for detecting a cardiac condition can beautomatically adjusted to suit the environment such that the cardiacevents are properly detected while reducing the likelihood of falsealarms. For example, while in a water operating mode, the ambulatorymedical device can reduce its sensitivity and/or wait for an extendedamount of time before determining that a cardiac condition is occurringdue to the heightened potential for false alarms in a wet environment.

In some implementations, sequences used by the ambulatory medical devicefor treating cardiac conditions can be based on the mode and/orenvironment that the ambulatory medical device is operating under. Forexample, when the ambulatory medical device is operating in the wateroperating mode (e.g., while the patient is taking a shower), the patientmay be slow to respond to treatment warnings. The ambulatory medicaldevice can afford the patient additional time to respond to a warningindicating that a treatment is about to be applied, thereby giving thepatient an adequate chance to stop the treatment while in a potentiallycompromising environment.

In some implementations, the way by which the ambulatory medical devicecan provide alarms to and receive input from the patient is based on thecurrent operating mode. For example, the ambulatory medical device mayprovide a relatively loud audible alarm when it is operating in theshower operating mode or the activity operating mode. The ambulatorymedical device may provide a tactile alarm when it is operating in thesleep operating mode.

In some implementations, the ambulatory medical device can automaticallyenter an operating mode based on one or more environmental conditionsidentified based on input from one or more sensors. For example, theambulatory medical device can automatically enter the water operatingmode based on information received from a moisture sensor. Theambulatory medical device can automatically enter the activity operatingmode or the sleep operating mode based on information received from amotion sensor and/or a pressure sensor.

Other features and advantages of the invention will be apparent from thedrawings, detailed description, and claims.

DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, components that are identical or nearly identical may berepresented by a like numeral. For purposes of clarity, not evercomponent is labeled in every drawing. In the drawings:

FIG. 1 is an example of a wearable medical device that includes amedical device controller.

FIGS. 2A-2B show an example of the medical device controller of FIG. 1.

FIG. 3A is a functional schematic of the medical device controller ofFIGS. 1 and 2A-2B.

FIG. 3B is a functional schematic of an example of a cardiac monitor.

FIG. 4A is an example flow diagram illustrating a methodology foradjusting operational parameters of the wearable medical device.

FIG. 4B is an example flow diagram illustrating a methodology forselecting an operating mode of the wearable medical device.

FIG. 5 is an example flow diagram illustrating a methodology forselecting a treatment sequence of the wearable medical device.

FIG. 6 is an example flow diagram illustrating a methodology forperforming the treatment sequence selected according to the methodologyillustrated in FIG. 5.

FIG. 7A shows an example of the wearable medical device being used inthe shower.

FIG. 7B is an example flow diagram illustrating a methodology forselecting the water operating mode of the wearable medical device.

FIG. 7C is an example flow diagram illustrating a methodology forselecting a treatment sequence of the wearable medical device.

FIG. 7D is an example flow diagram illustrating a methodology forperforming the treatment sequence selected according to the methodologyillustrated in FIG. 7C.

FIG. 8 shows an example of the wearable medical device being used whilea patient is sleeping.

FIG. 9 shows an example of the wearable medical device being used whilethe patient is active.

DETAILED DESCRIPTION

A medical device for use with the systems and techniques as disclosedherein can be configured to monitor one or more cardiac signals of apatient and determine whether the patient may be experiencing a cardiaccondition. For example, the medical device can include a plurality ofsensing electrodes that are disposed at various locations of thepatient's body and configured to sense or monitor the cardiac signals ofthe patient. In some implementations, the medical device can beconfigured to monitor, in addition to cardiac signals, otherphysiological parameters as described in further detail below. Forexample, the medical device can be used as a cardiac monitor in certaincardiac monitoring applications, such as mobile cardiac telemetry (MCT)and/or continuous event monitoring (CEM) applications.

In some implementations, the medical device can be configured todetermine an appropriate treatment for the patient based on the sensedcardiac signals and cause one or more therapeutic shocks (e.g.,defibrillating and/or pacing shocks) to be delivered to the body of thepatient. The medical device can include a plurality of therapyelectrodes that are disposed at various locations of the patient's bodyand configured to deliver the therapeutic shocks.

A medical device as described herein can be configured to monitor apatient for an arrhythmia condition such as bradycardia, ventriculartachycardia (VT) or ventricular fibrillation (VF). While the detectionmethods and systems described hereinafter are disclosed as detecting VTand VF, this is not to be construed as limiting the invention. Otherarrhythmias, such as, but not limited to, atrial arrhythmias such aspremature atrial contractions (PACs), multifocal atrial tachycardia,atrial flutter, and atrial fibrillation, supraventricular tachycardia(SVT), junctional arrhythmias, tachycardia, junctional rhythm,junctional tachycardia, premature junctional contraction, and ventricalarrhythmias such as premature ventricular contractions (PVCs) andaccelerated idioventricular rhythm, may also be detected. In someimplementations (e.g., implementations in which the medical device is atreatment device, such as a pacing and/or a defibrillating device), ifan arrhythmia condition is detected, the medical device canautomatically provide a pacing or defibrillation pulse or shock to treatthe condition.

In some implementations, a medical device can be configured todynamically and/or adaptively adjust one or more operational parametersof the medical device in response to patient, environmental and/orcontextual conditions. For example, dynamically adjusting operationalparameters includes adjusting the operational parameters insubstantially real-time as changes in the underlying patient,environmental and/or contextual conditions occur. For example, theoperational parameters may be adjusted after a delay from when a changein an underlying patient, environmental and/or contextual conditionoccurs. In some implementations, the delay may be based on apredetermined value. In some implementations, the delay isuser-configurable and provided through a user interface.

For example, a medical device can be configured to operate in a defaultoperating mode and one or more of a plurality of special modes inresponse to the patient, environmental and/or contextual conditions.Changes to the one or more operational parameters and/or an operatingmode in which the medical device operates can be based on the monitoredpatient signals (e.g., cardiac or other physiological signals of thepatient), and/or a selection input provided by a user and received atthe medical device.

For example, the one or more operational parameters may include sensingand/or monitoring parameters. Such sensing and/or monitoring parameterscan include detection parameters, criteria and/or conditions (e.g.,patient thresholds) that, if met, may indicate that the patient isexperiencing a medical condition. For example, a cardiac monitoringand/or treatment device may detect one or more cardiac conditions basedon such a set of operational parameters. Similarly, operationalparameters can include treatment parameters that control a therapydelivered by the device. For example, such treatment parameters maycontrol an intensity or a manner of therapy delivery. As described indetail below, medical devices described herein may be configured toadjust its operational parameters in response to changing patient,environmental, and/or contextual conditions. Other types of deviceoperational parameters may be adjusted or modified in response tochanging conditions based on the principles described herein. Forexample, such parameters can include, without limitation, communicationparameters (e.g., for controlling the transmission of data to and fromthe medical device), alarm and notification parameters (e.g., forcontrolling the types, manner, and modes of alerting the patient,bystanders, and/or caregivers), and/or other device operating parameters(e.g., relating to battery circuit parameters, device self-monitoringand testing parameters, energy storage parameters, etc.).

For example, a medical device may be configured to adjust one or moreoperational parameters based on a predetermined relationship with one ormore input signals from one or more sensors associated with the medicaldevice. For example, such adjustments may be made dynamically andautomatically in response to changing conditions. For example, theadjustments may occur within an open or closed loop system controlscheme. Further, such adjustments may be made adaptively in response tolearning patterns in the underlying changing conditions.

A predetermined relationship between the operational parameters andinput sensed signals as described above may be based on any known orlearned relationship between the underlying parameters, including singleor multi-variable linear, non-linear (such as quadratic, logarithmic,exponential, etc.), and other kinds of relationships. In some cases, thepredetermined relationship may be based on binary classifications,transformations of the underlying signals (e.g., discrete forms,frequency and/or other domains, etc.), and/or statistical analysis. Insome examples, the relationship may be based on performing amultivariate regression analysis of the input sensed signals andderiving one or more equations to describe the relationship.

Additionally, one or more techniques may be employed to match, verify,and/or correlate information from one or more types of sensors againstother types of sensors. For example, if a patient is performing aphysical activity such as running or jogging, the heart rate sensorinformation may be correlated with accelerometer information to confirmthe activity and the intensity of the activity.

The medical device may also be configured to analyze a plurality ofinput signals in order to adaptively effect changes to one or moreunderlying operational parameters. For example, the medical device mayeffect changes to the operational parameters based on a series ofdecision nodes. Each node may be based on logic implemented to test oneor more input signals (individually or in a predetermined combinedformat) from one or more sensors of the medical device against athreshold. An output of such decision nodes may cause one or moreoperational parameters of the medical device to be increased, decreased,or otherwise adjusted.

In some implementations, machine learning classification or regressiontools may be trained and validated on training/validation populations ofsensed values corresponding to signals from the one or more sensors.Such machine learning based systems can be implemented in accordancewith the principles described herein such that the medical device canadaptively adjust its operational parameters in accordance with changingpatient, environmental, and/or contextual conditions.

For example, in some implementations, a machine learning basedclassifier model (e.g., a random forest classifier model) may be trainedand validated on metrics relating to patient response button use (orother response mechanism) and corresponding ECG signals of the patientduring periods when the patient response buttons are used. Such a modelcan assess times at which patients push the response buttons and thecorresponding ECG signals to determine if the patient is conscious orundergoing a treatable condition. Once trained, the model can beadaptively validated and its corresponding thresholds can be adjustedover time for assessing new input response button uses and correspondingECG signals. In this way, the device can use machine learning toadaptively learn whether a treatable condition is likely when the devicedetects that the patient has pushed the response buttons based on priorhistorical data about the individual patient or a population ofpatients.

Any of the above techniques can be used alone or in combination in orderto establish a relationship between the operational parameters of themedical device and the sensed signals. In some situations, suchtechniques may be implemented within the one or more special operatingmodes as described herein.

Cardiac Devices

In one implementation, a cardiac monitoring and/or treatment device mayadjust its operational sensing or monitoring parameters in response tochanging conditions and/or patient input as described below. The cardiacdevice may be configured to monitor a patient's cardiac signals,including ECG signals, heart sounds, etc. For example, the cardiacdevice may include an axis analyzer to derive a signal representation ofthe electrical axis of the heart of a patient from whom ECG signals arereceived. Changes in the signal representation of the electrical axis ofthe heart can be evaluated to determine whether a treatable conditionexists (e.g., the patient is experiencing a cardiac condition). Forexample, the signal representation can include a magnitude component anda phase component. In some examples, the phase component can indicate azero-crossing indication. In some implementations, the analyzer can usea complex matched filter to analyze the ECG signals.

A treatable condition can be determined based on changes in the heartaxis information from a patient normal condition (e.g. baseline values,such as a baseline ECG recording). In this regard, a patient monitoredby the medical device may undergo an initial baselining process. Duringthe baselining process, a baseline set of information relating to thepatient is captured. For example, a baseline ECG recording may beobtained. The baseline ECG may have a length of approximately 30 secondsto one minute. The baseline ECG values are fed into the analyzer in theform of filter coefficient values corresponding to the filters used inthe analyzer. In particular, one or more specific comparisons of anincidence of zero phase crossing with periods of peaks of the magnitudecomponent of the heart axis representation can be used to indicate thetreatable condition. When the analyzer determines that a treatablecondition exists (e.g., the patient is experiencing a cardiaccondition), the analyzer can set a flag to indicate the condition.Additional details concerning a method for determining treatableconditions are disclosed in U.S. Pat. No. 5,944,669 (the “'669 patent”)entitled “Apparatus and method for sensing cardiac function,” thecontents of which are incorporated herein in its entirety.

In a default operating mode, once the baseline filter coefficientsvalues are input to the analyzer, the analyzer continuously monitors thephase component for zero crossing conditions and when detected, theanalyzer checks the magnitude component to determine whether themagnitude component is also above a magnitude threshold value. Forexample, the magnitude threshold value may be automatically calculatedbased on a prior history of the signal. Because amplitudes can varyaccording to a quality of the signal, the magnitude threshold value isallowed to vary within a preset of programmable range of values. In anexample, the magnitude threshold value can be set to less than 90% of apreviously detected peak level of the magnitude component.

In some examples, a sensitivity of the analyzer can be increased ordecreased to reduce a number of false positives due to increased patientmovement and/or activity. For example, changes to the sensitivity can bemade by changing corresponding parameters of the analyzer dynamically inresponse to the patient movement and/or activity. Patient movementand/or activity can be detected through one or more sensors such asaccelerometers, gyroscopes, tilt sensors, and the like. For example, aheart sounds sensor (e.g., which can be included in the wearable garmentand/or associated components) may detect increased heart sounds activityindicating that the patient is performing an activity. The sensor datacan be correlated with data from other sources to confirm that thepatient is performing an activity and provide information related to theintensity of the activity. An intensity of the movement can be detectedthrough one or more of such sensors. In some implementations, one ormore parameters of the analyzer can be adjusted in a predeterminedrelationship with the input from the one or more sensors. As describedabove, a variety of other ways to control the operational parameters ofthe device may be employed including, for example, machine learning andstatistical techniques, among others.

In order to increase or decrease the sensitivity of the analyzer, forexample, phase detection and/or magnitude threshold parameters can bechanged using any of the above techniques.

In some examples, to achieve decreased sensitivity (e.g., where anintensity of signal noise or patient movement increases), it may bedesirable to relax the requirements for declaring a match with baselinevalues. For example, the device may allow for more matching with one ormore baseline values (e.g., to increase matching the received ECG signalwith the baseline ECG recording, obtained as described above). To allowfor more frequent matching with baseline values, one or more phasedetection parameters can be changed. For example, a zero crossing rangecan be increased from a default range such that the zero crossingcondition detection rate is generally higher than the zero crossingcondition detection rate in the default operating mode. In someexamples, the magnitude threshold parameters can be changed. Forexample, the magnitude threshold value can be allowed to vary within agreater programmable range of values. For example, the magnitudethreshold value can be set to 70-80% of a previously detected peak levelof the magnitude component.

In some examples, the detection parameters may be changed when thedevice is in one or more special operating modes, such as a water oractivity mode. When the device is operating in a special operating mode,a sensitivity of the analyzer can be decreased in a manner similar tothat described above (e.g., to reduce a number of false positives due toincreased patient movement and/or activity). For example, phasedetection and/or magnitude threshold parameters can be changed. In someexamples, to allow for more frequent matching with baseline values, oneor more phase detection parameters can be changed. For example, a zerocrossing range can be increased from a default range such that the zerocrossing condition detection rate is generally higher than the zerocrossing condition detection rate in the default operating mode. In someexamples, the magnitude threshold parameters can be changed. Forexample, the magnitude threshold value can be allowed to vary within agreater programmable range of values. For example, the magnitudethreshold value can be set to 70-80% of a previously detected peak levelof the magnitude component.

In some examples, it may be desirable to increase a sensitivity of theanalyzer (e.g., by decreasing a zero crossing range from a default rangesuch that the zero crossing condition detection rate is generally lowerthan the zero crossing condition detection rate in the default operatingmode. For example, the magnitude threshold value can be configured tovary within a lesser range of values (e.g., 95% of the previouslydetected peak level of magnitude component).

Depending on patient, environmental, and/or contextual conditions, thedevice can be configured to automatically change a method of calculatingone or more patient metrics. As such, there may be additionaloperational differences in one or more operating modes of the device.For example, as described in the '669 patent, in a default operatingmode, a heart rate detector may be employed to determine whether thepatient's heart rate is elevated. For example, a QRS detector cananalyze signals from front-to-back (FB) electrodes and side-to-side (SS)electrodes and calculate FB and SS rates. These rates can be combinedwith an axis rate as determined by the axis analyzer and fed into a rateanalyzer to provide final heart rate information. In someimplementations, the heart rate can be calculated by averaging a rateobtained over a certain number of beats (e.g., five beats). For example,the averaging technique may be used in a default operating mode. Whenthe patient is physically active, however, the heart rate can be basedon a median value calculated from the multiple (e.g., five) beats. Assuch, when the device detects that the patient activity level hasincreased (e.g., beyond a predetermined threshold), the method ofcalculating the patient's heart rate information may automaticallychange. Similarly, in an activity operating mode, the method ofcalculating the heart rate may change.

In some implementations, when operating conditions change, a number ofbeats used for calculating the heart rate as described above can beincreased relative to the number of beats used by default. For example,the device may use eight, ten, or more beats to calculate the heart rateand thus be able to ride through noisy signals and/or events that may beencountered during certain operating conditions. In someimplementations, such as instances involving certain other specialoperating conditions, it may be desirable to reduce a number of beatsused to less than what is used in the default operating mode.

The device may be automatically or manual put in a special operatingmode (e.g., a water, activity, or other mode), depending on operatingconditions. While operating in a special operating mode, for example, anumber of beats used for calculating the heart rate as described abovecan be increased from what is used in a default operating mode. Forexample, the device may use eight, ten, or more beats to calculate theheart rate and thus be able to ride through noisy signals and/or eventsthat may be encountered during operation in the special mode. In someimplementations, such as instances involving certain other specialoperating modes, it may be desirable to reduce a number of beats used toless than what is used in the default operating mode.

The operational sensing, monitoring, and/or detection parameters caninclude heart rate parameters. For example, while operating undercertain operating conditions, heart rate thresholds may be changed inaccordance with one or more principles as described herein. Asbackground, if the patient's heart rate is sustained in an elevated zoneas determined based on predetermined rate thresholds, then the patientmay be experiencing a VT or VF event (e.g., assuming other detectionparameters are also met as described above). For example, thepredetermined rate thresholds can be input to the device via a userinterface module during initial setup for the device. For instance, thepredetermined rate thresholds may be set to a default value (e.g., 150beats per minute for a VT type event, and 200 beats per minute for a VFtype event). The default value may be adjusted to a new value (e.g., 160beats per minute for a VT type event, and 210 beats per minute for a VFtype event) via a user interface module.

In some implementations, while operating under certain operatingconditions, the predetermined rate thresholds may be increased ordecreased as appropriate depending on changes in the underlyingoperating conditions. For instance, if the patient is jogging orotherwise exercising, then the predetermined rate threshold may beconfigured to increase by a predetermined amount (e.g., five or tenbeats per minute over the rate thresholds set for the default operatingmode). As the patient's exercise intensity increases or decreases, thenumber of beats used in the calculation may be increased or decreased.

In some implementations, while operating under a special operating mode,the predetermined rate thresholds may be increased or decreased asappropriate. For example, if the special operating mode is an activitymode (such as when the patient is jogging or otherwise exercising), thenthe predetermined rate threshold may be configured to increase by a setamount (e.g., five or ten beats per minute over the rate thresholds setfor the default operating mode).

In some implementations, the device can employ a spectral analyzer thatuses fast Fourier transform (FFT), or other techniques, to measure andevaluate the respective SS and FB ECG input signal frequency components.For example, the presence of certain spectral components can beindicative of certain cardiac conditions as noted in detail below. Whileoperating in a default operating mode, the device may use a single FFTanalysis to provide an indication of a cardiac condition. Under someoperating conditions, the device may use a plurality (e.g., several) FFTanalyses to declare the condition. For example, the number of FFTanalyses may increase or decrease depending on the underlying changes inthe operating conditions. Similarly, while operating under some specialoperating modes, the device may use a plurality (e.g., several) FFTanalyses to declare the condition.

Changes in Cardiac Signal Noise Analysis

As noted above, the detection parameters for determining whether thepatient may be experiencing a cardiac condition may vary depending onthe operating conditions. For example, while operating in a shower orwater operating mode, the medical device may reduce its sensitivity bychanging one or more health metric thresholds (e.g., an ECG score asdescribed in further detail below). In some examples, the medical devicemay reduce its sensitivity by increasing an amount of detection time thedevice gives its noise algorithm (e.g., as explained in further detailbelow) to determine whether an identified event is a treatable VT/VFevent. While operating in the shower or water operating mode, thecardiac signals received by the medical device may not be completelyauthentic. For example, the cardiac signals may be affected by the wetenvironment or excessive patient movements in the shower and take on anappearance that is different than what it would be under more typicalconditions. The reduced sensitivity can account for potentiallyinaccurate ECG signals. For example, if the value meets or transgressesthe modified thresholds or if the device persists in declaring atreatable VT/VF event after an extended detection time, the medicaldevice may determine that the patient may be experiencing a cardiaccondition.

In some implementations, after the analyzer has detected a cardiaccondition, a noise detector can be executed to confirm the condition.For example, the noise detector can verify the detected condition todistinguish a treatable cardiac condition from inappropriate sensing of,for example, a VT/VF condition due to noise caused by lead malfunction,electromagnetic interference, patient movement, etc. For example, atransformed version of the patient's ECG signal, such as a frequencydomain representation of the signal, can be analyzed, a valuerepresenting at least one feature of the transformed ECG signal can beextracted, and an ECG score can be determined based on the at least onefeature of the transformed ECG signal. The transformed ECG signal canthen be compared to a threshold. For example, the transformed ECG signalmay be a presentation of a power distribution of the signal over a rangeof frequencies, which can be calculated from, for example, a frequencydomain representation of the ECG signal. For example, the transformedECG signal can be a power spectral density (PSD) signal, which describeshow the power of the ECG signal is distributed over differentfrequencies. For example, the noise detector may generate the PSD byperforming fast Fourier transform (FFT) operations on the time domainECG signal, or the noise detector may employ other discrete Fouriertransform (DFT) techniques to generate the PSD.

For example, a PSD of an ECG signal demonstrating VT/VF typically hasdistinct features. For example, the PSD of an ECG signal demonstratingVT/VF may have several distinct dominant spectral bands, while a normalsinus rhythm may have a dominant spectral band at less than 2.5 Hz. Thedominant spectral band is the band of frequencies that correspond to amaximum value of the PSD. A PSD with multiple dominant spectral bandshas more than one band of frequencies in which the power of the ECGsignal is significant. The information content in the PSD of the ECGsignal that is in VT/VF is spread over more frequencies, and thefrequency content is most dense around the frequency of the VT, which istypically greater than 2.5 Hz.

In addition, even in the presence of a substantial amount of noise, aPSD of normal sinus rhythm differs from a PSD of VT/VF arrhythmia. Noisewithin the ECG signal may be characterized as entropy (i.e.,randomness). Accordingly, various entropy calculations may be performedon a PSD to differentiate between a normal sinus rhythm signal withnoise and a VT/VF signal. For example, an in-band entropy may becalculated for a PSD of an ECG signal as described in co-pending U.S.application Ser. No. 14/791,836 (the “'836 application”), published asU.S. Patent Publication No. 2016/0000349, filed Jul. 6, 2015, entitled“SYSTEM AND METHOD FOR DISTINGUISHING A CARDIAC EVENT FROM NOISE IN ANELECTROCARDIOGRAM (ECG) SIGNAL,” the entire contents of which are herebyincorporated by reference. The first-band entropy may be calculated byconverting the PSD to a probability distribution function (PDF) andcalculating the entropy of the signal between 0 Hz and 2 Hz. The fourfeatures of the PSD (a dominant frequency of the PSD; in-band entropy ofthe PSD between frequencies of 2 Hz and 6 Hz; first-band entropy of thePSD between frequencies of 0 Hz and 2 Hz; and a variance of the PSD,which is extracted as described below) were selected as the featuresthat would be extracted from the PSD and submitted to a machine learningclassifier based on a combination of feature selection experimentationand physiological reasoning.

When a normal sinus rhythm (NSR) in the absence of noise is compared toan NSR contaminated with motion artifact or machine noise, somecharacteristics of the PSD remain the same. For example, because entropyis a measure of randomness, the entropy in the 0-2 Hz range of the PSDis similar for an NSR with and without noise. However, the PSD for anNSR without the presence of noise typically has much less informationcontent in the 2-6 Hz range than a PSD for an NSR with a noisy signal.Variance can be selected as a feature that would be extracted from thePSD and submitted to the machine learning classifier because thevariance of a distribution provides a “feel” for the relative spread ofthe distribution. If a PSD has most of the energy in the 0-2 Hz band andvery little energy in the 2-6 Hz band, the variance is relatively small.However, a PSD with much energy in the 2-6 Hz band would provide a muchwider variance of the PSD. A PSD for an NSR has most of the energy inthe 0-2 Hz band, and a PSD for a VT/VF arrhythmia has more energy in the2-6 Hz band. In order to calculate variance, it can be assumed that thePSD is a normal distribution, and the variance of the PSD is calculatedby treating the PSD as a PDF and calculating the second moment.

After the features are extracted from the PSD, the features can be fedinto the machine learning classifier. For example, as described in the'836 application, the classifier may be trained on data sets includingnoisy normal sinus rhythm signals (e.g., false positive detections) andtachyarrhythmia signals. For example, two classifiers for each detectionchannel (e.g., side-to-side channel and front-to-back channel) can beused, where each classifier produces a numerical value in a range from 0to 1. For example, a 20-second buffer of an ECG signal is passed from ashared memory to be analyzed. An ECG score is compiled based on theoutputs from the evaluation of each second of analysis as a master scorecovering the 20 seconds of ECG signal. Fewer or additional ECG signalcan be used in evaluating the ECG score (e.g., the analysis can span afew seconds to multiple minutes, hours, or even days).

While operating in a default operating mode, for example, a thresholdscore for the noise classification can be selected to have a value of10. That is, if the score is above 10, then the noise detection confirmsthe cardiac condition. Control then passes to the treatment sequence.However, if the score is less than 10, then the event can be classifiedas noise and the treatment sequence can be held off while a new score iscreated based on continued monitoring. If the score goes above 10, thenthe treatment sequence is initiated.

Under certain operating conditions, such as when the patient is in theshower or performing an activity, a sensitivity of the noise detectorcan be decreased (e.g., and a specificity can be increased) to reduce anumber of false positives due to increased patient movement and/oractivity. For example, adjustments may be made dynamically orautomatically in relation to the level or intensity of the humidityexposure and/or the activity. In some examples, the threshold ECG scorecan be raised (e.g., to 12, 15 or more) depending on the input signalsfrom the sensors. For example, as a humidity sensor senses high humidityand/or water levels, the threshold ECG score may be automatically raisedaccording to a predetermined relationship with the level of detectedhumidity. Similarly, as a motion sensor senses increased or decreasedpatient physical activity and/or movement, the threshold ECG score maybe automatically raised or decreased according to a predeterminedrelationship with the level of detected activity or movement.

In some examples, the device may be put in a special operating modeunder certain operating conditions. As such, in one of the specialoperating modes, (e.g., a water or activity mode as described herein), asensitivity of the noise detector can be decreased (e.g., and aspecificity can be increased) to reduce a number of false positives dueto increased patient movement and/or activity. In one example, thethreshold ECG score can be raised (e.g., to 12, 15 or more). Forexample, the threshold ECG score for the special operating mode can bepreset by a user through a user configuration screen (e.g., during aninitial fitting and/or baselining process). In some implementations,such as instances involving certain special operating modes, asensitivity of the noise detector can be increased (e.g., by decreasingthe threshold ECG score to be less than the threshold ECG score in thedefault operating mode. In some implementations, the threshold ECG scorecan be decreased to 8, 7, or less.

In some implementations, the cardiac signal can undergo one or morepreprocessing and/or noise detection steps (e.g., based on a machinelearning classifier algorithm), and in some implementations, the ECGscore may be processed or converted into a different form before it iscompared to the threshold. If the ECG score meets or exceeds thethreshold, the medical device may determine that the patient may beexperiencing a cardiac condition.

Changes in Device Treatment Parameters

After it is determined that the patient may be experiencing a cardiaccondition, the medical device can be configured to select a treatmentsequence for treating the particular condition. Depending on theoperating mode, for example, the medical device may be configured todetermine that a series of defibrillation shocks at particularintensities is appropriate for treating the cardiac condition. In someimplementations, the device can issue up to five bi-phasic shocks if thedevice determines that the cardiac condition is present after eachpreceding shock.

For each of the special operating modes, a caregiver or other designeecan change, via a user interface module, a number of pulses, or shocktreatment parameters for each of the five pulses. For example, the usermay set a water mode treatment sequence to include all five bi-phasicpulses, and may set each of the pulses to be delivered with escalatingenergy levels.

In certain operating conditions, the treatment parameters may have apredetermined relationship with the signals from the environmental,contextual, and/or patient sensors. As the sensed signals from thesensors change over time, the treatment parameters may be dynamicallyadjusted to conform to the current operating condition. In someexamples, depending on the sensed signals, the treatment parameters maybe adjusted to deliver more or less energy per pulse to the patient asthe patient and/or the environment in which the device operates changes.Similarly, one or more profiles and/or shapes of the pulse may bedynamically shaped or adjusted in response to the operating conditions.

Changes in Alarms and/or Notifications

The medical device may provide one or more indications (e.g., warningsor alerts) to the patient that a treatment shock is about to bedelivered before it is actually delivered to the patient. The one ormore indications may be in various forms. For example, one or moreindications may be haptic, and one or more indications may be audible.In some implementations, a first indication is a haptic indication thatis intended to attract the patient's attention without disturbingothers, a second indication is a low volume audible alert, and a thirdindication is a high volume audible alert.

In some implementations, as the operating conditions change over time,any or all of the duration and/or number, and/or types of indications,and/or sequence of indications may be dynamically changed or adjusted inaccordance with a predetermined relationship with one or more sensedsignals. For example, as the patient's activity increases, it is lesslikely that the patient will be able to respond quickly to certainalarms. As such, an amount of time provided to respond to an alarm maybe increased in proportion to the amount of detected activity.Similarly, an intensity of an audible alarm may automatically increasein proportion to an amount of detected ambient noise.

In some implementations, for each of the default and/or specialoperating modes, all of the duration and/or number, and/or types ofindications, and/or sequence of indications can be user configurable viaa user interface. For example, a caregiver may determine that for aparticular patient it is desirable to, in a patient sleep mode, skip thehaptic alarm and proceed directly to the low-volume audible alarm. Inaddition, the caregiver may lengthen the duration of the low-volumeaudible alarm in the patient sleep mode relative to the duration of thelow-volume audible alarm in the default mode for the patient. Additionaltechniques for adapting alarms according to one or more detectedconditions are disclosed in U.S. Patent Publication No. 2012/0293323(the “'323 publication”), entitled “System and method for adaptingalarms in a wearable medical device,” the contents of which areincorporated herein in their entirety.

On perceiving the alarm, the patient may be able to instruct the medicaldevice to refrain from delivering the treatment shock. For example, thepatient may instruct the medical device to refrain from applying atreatment shock if the patient is well and the medical device falselyidentified a cardiac event. Information related to the initial treatmentdetermination, the indication that the treatment is about to bedelivered, and the way by which the patient can stop the treatment fromoccurring is generally referred to as the treatment sequence.

The treatment sequence may be selected based at least in part on theparticular mode that the medical device is operating under at the time.For example, while operating under a default operating mode, the medicaldevice may give the patient 30 seconds to stop a selected treatment frombeing applied. In contrast, while operating under a special (e.g.,non-default) operating mode (e.g., a water or activity mode), themedical device may give the patient an extended amount of time (e.g., 45seconds) to stop a selected treatment from being applied.

Example Medical Devices

In some implementations, the medical device as described herein is anexternal or non-invasive medical device (e.g., in contrast to internalor invasive devices, such as implantable medical devices). For example,the external medical device can be a cardiac monitoring and/or automatedpacing device or defibrillator, such as an in-facility continuousmonitoring defibrillator (e.g., for patients that are confined to alimited space within a facility, such as, within a hospital environment,to a patient's room) or an outpatient wearable defibrillator.

In some implementations, an external medical device can be an automatedcardiac monitor or defibrillator that can be used in certain specializedconditions and/or environments such as in combat zones or withinemergency vehicles. The medical device can be configured so that it canbe used immediately (or substantially immediately) in a life-savingemergency. For example, the external medical device can be an automatedexternal defibrillator (AED). Such AEDs are available from ZOLL® MedicalCorporation of Chelmsford, Mass.

In some implementations, the external medical device is an ambulatorydevice (e.g., a device that is capable of and designed for moving withthe patient as the patient goes about his or her daily routine). In someexamples, the external medical device can be configured as a wearabledefibrillator, such as the LifeVest® wearable defibrillator availablefrom ZOLL® Medical Corporation of Chelmsford, Mass.

The devices as described herein may be capable of continuously,substantially continuously, long-term and/or extended use or wear by, orattachment or connection to a patient.

For example, devices as described herein may be capable of being used orworn by, or attached or connected to a patient, without substantialinterruption for a predetermined period of time. In some examples, thedevices described herein may be capable of being used or worn by, orattached or connected to a patient for example, up to hours or beyond(e.g., weeks, months, or even years).

In some implementations, the devices described herein may be removed fora period of time before use, wear, attachment, and/or connection to thepatient is resumed (e.g., to change batteries, to change the garment,and/or to take a shower), without departing from the scope of theexamples described herein.

The devices as described herein may be capable of continuously,substantially continuously, long-term and/or extended monitoring of apatient. For example, devices as described herein may be capable ofproviding cardiac monitoring without substantial interruption for apredetermined period of time. In some examples, the devices describedherein may be capable of continuously or substantially continuouslymonitoring a patient for cardiac-related information (e.g., ECGinformation, including arrhythmia information, heart sounds, etc.)and/or non-cardiac information (e.g., blood oxygen, the patient'stemperature, glucose levels, and/or lung sounds), for example, up tohours or beyond (e.g., weeks, months, or even years).

In some implementations, the devices described herein may be powereddown for a period of time before monitoring is resumed (e.g., to changebatteries, to change the garment, and/or to take a shower), withoutdeparting from the scope of the examples described herein.

In some instances, the device may carry out its monitoring in periodicor aperiodic time intervals or times. For example, the monitoring duringintervals or times can be triggered by a user action or another event.For example, one or more durations between the periodic or aperiodicintervals or times can be user-configurable.

In various implementations, the devices may be operated on battery powerfor a duration of the device's use after which the batteries may bereplaced and/or recharged.

In some implementations, the medical device as described herein can be ahospital based medical device including, for example, a cardiacmonitoring device, a defibrillator and/or pacing device. For example,the hospital based device can include a defibrillator and/or pacingdevice configured for continuous or substantially continuous use, wear,connection, attachment, or monitoring by/to/of a patient in a hospitalenvironment. The hospital based device can include a plurality oftherapy and sensing electrodes that are attached to the patient's skin.In some examples, the sensing and/or therapy electrodes are disposableadhesive electrodes. In some implementations, the electrodes are affixedto an electrode assembly (e.g., a patch), which can then be adhesivelyattached to the patient's skin. The sensing and/or therapy electrodes,and/or integrated electrodes can be attached to the patient's skin atparticular locations as prescribed by a trained professional.

In some implementations, the medical device as described herein can beconfigured to monitor a patient presenting with syncope (e.g., byanalyzing the patient's cardiac activity for aberrant patterns that canindicate abnormal physiological function). In some examples, aberrantpatterns may occur prior to, during, or after the onset of syncopesymptoms. For example, the short-term outpatient defibrillator caninclude a plurality of electrodes and/or an electrode assembly (e.g., apatch) that can be adhesively attached to the patient's skin. Thepatient may replace the electrodes and/or patches as prescribed by atrained professional.

For example, the medical device can include a user interface forinteracting with the medical device. The device can include one or moreinput mechanisms (e.g., buttons) that the patient can interact with inorder to respond to a treatment alert. In some examples, the medicaldevice issues a treatment alert before providing a treatment shock, andif the patient does not respond to the treatment alert (e.g., by holdingdown one or more response buttons), the device can deliver the treatmentshock to restore normal heart rhythm.

Example Wearable Medical Device

FIG. 1 illustrates an example wearable medical device 100. The wearablemedical device 100 includes a plurality of sensing electrodes 112 thatcan be disposed at various positions about the patient's body. Thesensing electrodes 112 are electrically coupled to a medical devicecontroller 120 through a connection pod 130. In some implementations,some of the components of the wearable medical device 100 are affixed toa garment 110 that can be worn on the patient's torso. For example, asshown in FIG. 1, the controller 120 can be mounted on a belt worn by thepatient. The sensing electrodes 112 and connection pod 130 can beassembled or integrated into the garment 110 as shown. The sensingelectrodes 112 are configured to monitor the cardiac function of thepatient (e.g., by monitoring one or more cardiac signals of thepatient). While FIG. 1 shows three sensing electrodes 112, additionalsensing electrodes may be provided, and the plurality of sensingelectrodes 112 may be disposed at various locations about the patient'sbody.

The wearable medical device 100 can also optionally include a pluralityof therapy electrodes 114 that are electrically coupled to the medicaldevice controller 120 through the connection pod 130. The therapyelectrodes 114 are configured to deliver one or more therapeuticdefibrillating shocks to the body of the patient if it is determinedthat such treatment is warranted. The connection pod 130 may includeelectronic circuitry and one or more sensors (e.g., a motion sensor, anaccelerometer, etc.) that are configured to monitor patient activity. Insome implementations, the wearable medical device 100 may be amonitoring only device that omits the therapy delivery capabilities andassociated components (e.g., the therapy electrodes 114). In someimplementations, various treatment components may be packaged intovarious modules that can be attached to or removed from the wearablemedical device 100 as needed.

The controller 120 includes response buttons (210 of FIGS. 2A-2B) and atouch screen (220 of FIGS. 2A-2B) that the patient can interact with inorder to communicate with the medical device 100. The controller 120also includes a speaker (230 of FIGS. 2A-2B) for communicatinginformation to the patient and/or a bystander. In some examples, whenthe controller 120 determines that the patient is experiencing cardiacarrhythmia, the speaker can issue an audible alarm to alert the patientand bystanders to the patient's medical condition. In some examples, thecontroller 120 can instruct the patient to press and hold one or both ofthe response buttons on the medical device controller 120 to indicatethat the patient is conscious, thereby instructing the medical devicecontroller 120 to withhold the delivery of one or more therapeuticdefibrillating shocks. If the patient does not respond to an instructionfrom the controller 120, the medical device 100 may determine that thepatient is unconscious and proceed with the treatment sequence,culminating in the delivery of one or more defibrillating shocks to thebody of the patient.

FIGS. 2A (front view) and 2B (rear view) show an example of the medicaldevice controller 120 of FIG. 1. The controller 120 may be powered by arechargeable battery 212. The rechargeable battery 212 may be removablefrom a housing 206 of the medical device controller 120 to enable apatient and/or caregiver to swap a depleted (or near depleted) battery212 for a charged battery. The controller 120 includes a user interfacesuch as a touch screen 220 that can provide information to the patient,caregiver, and/or bystanders. The patient and/or caregiver can interactwith the touch screen 220 to control the medical device 100. Thecontroller 120 also includes a speaker 204 for communicating informationto the patient, caregiver, and/or the bystander. The controller 120includes one or more response buttons 210. In some examples, when thecontroller 120 determines that the patient is experiencing cardiacarrhythmia, the speaker 204 can issue an audible alarm to alert thepatient and bystanders to the patient's medical condition. In someexamples, the controller 120 can instruct the patient to press and holdone or both of the response buttons 210 to indicate that the patient isconscious, thereby instructing the medical device controller 120 towithhold the delivery of therapeutic defibrillating shocks. If thepatient does not respond to an instruction from the controller 120, themedical device 100 may determine that the patient is unconscious andproceed with the treatment sequence, culminating in the delivery of oneor more defibrillating shocks to the body of the patient. The medicaldevice controller 120 may further include a port 202 to removablyconnect sensing electrodes (e.g., sensing electrodes 112) and/ortherapeutic electrodes (e.g., therapy electrodes 114), and/or electrodepatches, to the medical device controller 120.

FIG. 3A shows a schematic of an example of the medical device controller120 of FIGS. 1 and 2A-2B. The controller 120 includes a processor 318,an operating condition analyzer 320, one or more sensors 321, a cardiacevent detector 324, a patient sensor interface 312, an optional therapydelivery interface 302, data storage 304 (which may include patient datastorage 316), an optional network interface 306, a user interface 308(e.g., including the touch screen 220 shown in FIG. 2), and a battery310. The patient sensor interface 312 is coupled to the patient sensingelectrodes 112, and the therapy delivery interface 302 (if included) iscoupled to the patient therapy or treatment electrodes 114. The patientsensor interface 312 and the therapy delivery interface 302 implement avariety of coupling and communication techniques for facilitating theexchange of data between the patient electrodes 112, 114 and thecontroller 120.

In some implementations, the processor 318 can perform a series ofinstructions that control the operation of the other components of thecontroller 120. The cardiac event detector 324 is configured to monitorthe cardiac activity of the patient and identify cardiac eventsexperienced by the patient based on received cardiac signals. In someexamples, the cardiac event detector 324 can access patient baselineinformation in the form of templates (e.g., which may be stored in thedata storage 304 as patient data 316) that can assist the cardiac eventdetector 324 in identifying cardiac events experienced by the particularpatient, as described above. In some examples, the network interface 306can facilitate the communication of information between the controller120 and one or more other devices or entities over a communicationsnetwork. In some examples, the network interface 306 is configured tocommunicate with a server (e.g., a remote server 326). A caregiver canaccess the data from the remote server 326 to access information relatedto the patient.

The operating condition analyzer 320 can be configured to, responsive toon one or more environmental and/or contextual conditions (e.g., assensed by sensors 321) and/or the monitored cardiac signals of thepatient (e.g., as sensed by electrodes 112) and/or a selection inputprovided by a user (e.g., through user interface 308), cause thecontroller 120 to change one or more operational parameters and/or anoperation mode of the device 100.

For example, sensors 321 can include one or more sensors to detectoperating conditions of the medical device including environmentaland/or contextual conditions. The sensors 321 can include one or more ofmotion sensors, resistive potentiometers, capacitive sensors,differential transformers, accelerometers, humidity sensors, pressuresensors, position sensors, force sensors, shock sensors, piezo sensors,strain gauges, optical sensors, moving-coil sensors, temperaturesensors, imaging sensors, electro-optical sensors, sound sensors,microphones, ultrasonic sensors, radiation sensors, and flow sensors,among others.

Example Monitoring Medical Device

In some examples, the medical device may be a patient monitoring device.For example, the patient monitoring device may be configured to monitorone or more of a patient's physiological parameters without anaccompanying treatment component. For example, a patient monitor mayinclude a cardiac monitor for monitoring a patient's cardiacinformation. The cardiac information can include, without limitation,heart rate, ECG data, heart sounds data from an acoustic sensor, andother cardiac data. In addition to cardiac monitoring, the patientmonitor may perform monitoring of other relevant patient parameters,including glucose levels, blood oxygen levels, lung fluids, lung sounds,and blood pressure.

FIG. 3B illustrates an example cardiac monitoring medical device, forexample, a cardiac monitor 350. In some implementations, the cardiacmonitor 350 is capable of and designed for being worn by a patient whois at risk of developing cardiac problems, but who does not yet meetcriteria to be outfitted with a medical device that includes a treatmentcomponent (e.g., a defibrillator). Thus, the cardiac monitor 350 may beprescribed so that continuous and/or event-based data can be sent fromthe cardiac monitor 350 to a server (e.g., the remote server 352). Insome implementations, the remote server 352 is the same as the server(326 of FIG. 3A) described above. A caregiver can access the data fromthe remote server 352 and determine whether the patient is experiencingor has experienced a cardiac problem. In some implementations, afterdetermining that the patient is experiencing a cardiac problem, thecaregiver may instruct the patient to begin wearing a medical devicewith treatment capabilities.

The cardiac monitor 350 includes a medical device controller (e.g., amedical device controller similar to the controller 120 described abovewith reference to FIGS. 1 and 2A-2B) along with associated components.In an implementation, the medical device controller 120 operates in asimilar fashion as described above. The cardiac monitor includes theplurality of sensing electrodes 112. In some examples, the sensingelectrodes 112 can be an integral part of a housing structure of thecardiac monitor 350.

In some implementations, the patient can interact with the userinterface 308 to identify a patient symptom. The user interface 308 mayinclude a drop down menu or check list that allows the patient to selecta particular symptom from a list. Options for patient systems caninclude one or more of: feeling a skipped beat, shortness of breath,light headedness, racing heart rate, fatigue, fainting, chestdiscomfort, weakness, dizziness, and/or giddiness. In addition, thepatient can select a level of activity (e.g., light activity, moderateactivity, rigorous activity, etc.) that he or she was performing whenthe symptom occurred. In some implementations, in response to theselection by the patient, the cardiac event detector 324 can cause aportion of patient physiological information (e.g., in the form of acardiac signal) to be captured for a length of time that is based on atime at which the symptom was experienced. For example, the cardiacevent detector 324 can cause a portion of an ECG signal of the patientto be captured. The portion of the ECG signal is sometimes referred toherein as an ECG strip. In some implementations, the cardiac monitor 350can continuously record ECG data while simultaneously identifying andrecording one or more ECG strips relating to one or more events ofinterest (e.g., patient-reported symptoms, events detected by thecardiac event detector 324, etc.). As such, if a caregiver wishes toview ECG data for a period of time prior to or after the recorded ECGstrip relating to an event of interest, such data is available forreview from the continuously-recorded ECG data.

The operating condition analyzer 320 can be configured to operate in amanner similar to that previously described in connection with FIG. 3A.Accordingly, the operating condition analyzer 320 can be configured to,responsive to on one or more environmental and/or contextual conditions(e.g., as sensed by sensors 321) and/or the monitored cardiac signals ofthe patient (e.g., as sensed by electrodes 112) and/or a selection inputprovided by a user (e.g., through user interface 308), cause thecontroller 120 to change one or more operational parameters and/or anoperation mode of the device 100.

Dynamically Adjusting Operational Parameters

FIG. 4A is an example flow diagram 400A illustrating a methodologyperformed to monitor one or more external sensors (e.g., the sensors 321and/or the sensing electrodes 112 of FIGS. 3A-3B) and dynamically adjustdevice operational parameters in accordance with input from the externalsensors. In this way, device operational parameters are adjusted inaccordance with changes to patient, environmental, and/or contextualconditions. In some implementations, the methodology for adjusting oneor more operational parameters can be initiated (block 402) by atriggering event, such as upon receiving an input from the user (block408), or some other external event based on an input sensed signalreceived from one or more sensors or patient electrodes. In someimplementations, one or more changes in patient, environmental, and/orcontextual conditions are detected (block 404). For example, the inputsensed signal may be a change in humidity or water sensed by a humidityand/or fluid sensor. Changes in one or more patient, environmental,and/or contextual conditions are monitored (block 406). A change in thehumidity that meets or exceeds a predetermined threshold can initiatethe process to adjust one or more device operational parameters inaccordance with the changes (block 410). For example, the one or moreoperational parameters may be sensing and/or detection criteria asdescribed in detail above. When an underlying predetermined change inone or more sensed signals is detected, the operational parameters maybe adjusted according to a predetermined relationship with the one ormore sensed signals.

In some implementations, the methodology for adjusting the operatingparameters may be continuously running (e.g., the wearable medicaldevice 100 is continuously in a state in which the operating parametersare adjusted in response to changing operating conditions). For example,the wearable medical device 100 can include one or more sensors such asa moisture sensor, a motion sensor (e.g., an accelerometer, a gyroscope,etc.), a pressure sensor (e.g., a strain gauge), and/or a locationsensor (e.g., a GPS receiver). The wearable medical device 100 canreceives signals from the one or more sensors, and the processor 318 canprocess the signals to ascertain environmental data (e.g., informationrelated to environmental conditions.) The wearable medical device 100can also monitor input (e.g., cardiac and/or other patient physiologicalsignals) received from the patient sensors.

Over a period of time, the device 100 can monitor changes in thepatient, environmental, and/or contextual conditions, and increases ordecreases values corresponding to the one or more operating parametersin accordance with a predetermined relationship.

For example, briefly referring to FIG. 7A, a moisture sensor 702 of thewearable medical device 100 may provide a signal to the processor 318that indicates that the patient is in a humid environment (e.g., in theshower). As the signals received from the moisture sensor 702 indicatechanging moisture content over a period of time, the wearable medicaldevice 100 may automatically adjust (e.g., increase or decrease) asensitivity of the cardiac detection algorithm in the manner describedabove.

In some implementations, the wearable medical device 100 also monitorscardiac signals received by the sensing electrodes 112 and considersthese signals instead of or in addition to the environmental conditiondata in adjusting the operational parameters. For example, if thecardiac data indicates that the patient's heart rate is in an elevatedstate, then the device may cause the sensitivity of the cardiacdetection algorithm to decrease according to a predeterminedrelationship with the amount of heart rate elevation. For example, ifmotion sensors detect that the patient is performing a vigorousactivity, the cardiac detection parameters may be dynamically changed todecrease the sensitivity of the cardiac detection algorithm. Forexample, if the patient's heart rate is at or around 20% over thepatient's regular average heart rate, the arrhythmia heart ratethreshold may be correspondingly raised by 5% of the previous threshold.Similarly, if the patient's heart rate is at or around 20% over thepatient's regular average heart rate, the amount of time to declare anarrhythmia event may be correspondingly increased by 10% of the previousthreshold to give the device more time to analyze the ECG signal.Various other configurations may be employed where the level of activity(e.g., as detected by motion sensors) and/or the patient's current heartrate may have a predetermined relationship with the sensing and/ordetection criteria. Thus, the timing threshold may be dynamicallyincreased or decreased depending on the patient's activity. In thismanner, changes in the output signals from the activity sensors and/orthe heart rate sensors can act as a surrogate for the level of noisyartifacts in the ECG signal.

In some implementations, a user may be able to manually adjust one ofmore of the device operational parameters (block 408). For example, auser can manually cause the wearable medical device 100 to adjust thedetection and/or treatment criteria using one or more input mechanisms,such as the touch screen 220 and/or a button on the medical devicecontroller 120 and/or input mechanisms on other components of thewearable medical device (e.g., on the user interface pod 140).

Before, during, and/or after operating parameters are adjusted, thewearable medical device 100 can continue to monitor the cardiac signalsreceived by the sensing electrodes 112 to determine whether the patientmay be experiencing a cardiac conditions that may require treatment.

Medical Device Operating Modes

In some examples, the external medical device 100 of FIG. 1 can operatein a default mode, a water or shower mode, a patient sleep mode, and/oran activity mode, among others.

Selecting, Entering, and Exiting an Operating Mode

FIG. 4B is a flow diagram 400B illustrating a methodology performed toselect an operating mode. The methodology for selecting an operatingmode is initiated (block 412). In some implementations, the methodologyis initiated by a triggering event, such as upon receiving an input fromthe user, or some other external event. In some implementations, themethodology for selecting an operating mode is continuously running(e.g., the wearable medical device 100 is continuously in a state inwhich an operating mode can be selected). The wearable medical device100 is configured to monitor one or more patient, environmental, and/orcontextual conditions (block 414). For example, the wearable medicaldevice 100 can include one or more sensors such as a moisture sensor, amotion sensor (e.g., an accelerometer, a gyroscope, etc.), a pressuresensor (e.g., a strain gauge), and/or a location sensor (e.g., a GPSreceiver). The wearable medical device 100 receives signals from the oneor more sensors, and the processor 318 processes the signals toascertain patient, environmental, and/or contextual data (e.g.,information related to patient, environmental, and/or contextualconditions.) The wearable medical device 100 also monitors input (e.g.,cardiac and/or other patient physiological signals) received from themonitoring component (block 416). The operating mode can then beselected (block 420). The selection may be based at least in part on atleast one of i) the one or more patient, environmental, and/orcontextual conditions, and ii) the input received from the monitoringcomponent. The selected mode can correspond to a state of the patientbeing monitored by the wearable medical device 100.

In some implementations, while the device 100 is in a particularoperating mode (e.g., a special or non-default operating mode), thedevice 100 can monitor for one or more patient, environmental, and/orcontextual conditions that indicate that the device 100 should return toa default operating mode, or enter another operating mode.

For example, briefly referring to FIG. 7A, a moisture sensor 702 of thewearable medical device 100 may provide a signal to the processor 318that indicates that the patient is in a humid environment (e.g., in theshower). If the signals received from the moisture sensor 702 indicate amoisture content that meets or transgresses a threshold (e.g., apredetermined threshold), the wearable medical device 100 may enter thewater or shower mode. When the signals received from the moisture sensor702 indicates a moisture content that falls below the threshold (or asecond, different predetermined threshold), the device 100 may exit thewater or shower mode and return to a default operating mode. In someexamples, the device 100 may be configured to automatically switch tothe default operating mode after a predetermined amount of time haselapsed. The amount of time that the device 100 remains in a specialoperating mode can be configured by a user. For example, a user maypreconfigure the device 100 to exit the shower or water mode after 30minutes has elapsed. For example, the patient or other user may bealerted or prompted by the device 100 to provide input confirming thatthe device 100 should exit the special operating mode and return to thedefault operating mode. As noted above, the device may also switch to adifferent special operating mode from a current special operating mode.

In some implementations, the wearable medical device 100 also monitorscardiac signals received by the sensing electrodes 112 and considerssuch cardiac signals instead of or in addition to the environmentalcondition data in selecting an operating mode. For example, if thecardiac data indicates that the patient's heart rate is in an elevatedstate for a predetermined amount of time, then the device may enter theactivity mode. For example, the threshold heart rate may be set to 100beats per minute, and the predetermined amount of time may be set to 120seconds or 2 minutes. One or more other thresholds and/or times may bepossible. In some examples, the threshold and/or time may be userconfigurable via a user interface (e.g., during initial setup and/orbaselining and/or patient fitting).

Other examples of mode selection based on patient, environmental, and/orcontextual conditions and/or input received from the monitoringcomponent are described in more detail below with respect to water mode,patient sleep mode, and activity mode, among others.

In some implementations, the user may be prompted to confirm a modechange before the device effects the change in device mode. For example,the device may automatically enter a mode after a predetermined timeoutperiod (e.g., 10-45 seconds, 1-2 minutes, or more) during which a user'sresponse to such a prompt is not received. For example, thepredetermined timeout period may be user configurable via a userinterface (e.g., during initial setup and/or baselining and/or patientfitting).

In some implementations, the operating mode can be selected based on aninput received by the wearable medical device 100 from a user (block418). For example, a user can manually cause the wearable medical device100 to enter a particular mode using one or more input mechanisms, suchas the touch screen 220 and/or a button on the medical device controller120 and/or input mechanisms on other components of the wearable medicaldevice (e.g., on the user interface pod 140).

Before, during, and/or after an operating mode is selected, the wearablemedical device 100 can continue to monitor the cardiac signals receivedby the sensing electrodes 112 to determine whether the patient may beexperiencing a cardiac conditions that may require treatment. Theselected operating mode can determine the particular detection criteriaor parameters (e.g., patient parameter conditions) that are used todetermine whether the patient may be experiencing a cardiac condition.

In some examples, after the device 100 enters an operating mode, thedevice 100 may be configured to re-baseline the patient. As previouslynoted, a treatable condition can be determined based on changes in theheart axis information from a patient normal condition (e.g. baselinevalues, such as a baseline ECG recording). In this regard, a patientmonitored by the medical device can be prompted to carry out are-baselining process to prepare new ECG templates to be used when themedical device is in the special operating mode. In someimplementations, the re-baselining process can occur automatically inresponse to detecting a change in operating modes. During are-baselining process, a baseline set of information relating to thepatient can be captured as the new set of templates for detectingtreatable conditions in the special operating mode.

In some examples, after the device 100 exits an operating mode, thedevice 100 may be configured to re-baseline the patient. As previouslynoted, a treatable condition can be determined based on changes in theheart axis information from a patient normal condition (e.g. baselinevalues, such as a baseline ECG recording). In this regard, a patientmonitored by the medical device can be prompted to carry out are-baselining process to prepare new ECG templates. In someimplementations, the re-baselining process can occur automatically inresponse to detecting a change in operating modes. During are-baselining process, a baseline set of information relating to thepatient can be captured as the new set of templates for detectingtreatable conditions in the default operating mode. Additional detailsconcerning a method for baselining patients and determining treatableconditions based on the baselining are disclosed in the '669 patentdescribed above.

Selecting a Treatment Sequence

FIG. 5 is a flow diagram 500 illustrating a methodology performed toselect a treatment sequence. The methodology for selecting a treatmentsequence may be initiated (block 502) automatically. For example, thewearable medical device 100 may continuously monitor the cardiac signalsreceived by the sensing electrodes 112 to determine whether the patientmay be experiencing a cardiac conditions that may require treatment.Before a special operating mode is selected by the wearable medicaldevice 100, the detection parameters (e.g., conditions) for identifyinga cardiac condition may be a default set of parameters. Each specialoperating mode may be associated with one or more predefined detectionparameters. Thus, before determining whether the patient may beexperiencing a cardiac condition, the methodology can first identify theselected operating mode (block 504).

The identification of the selected operating mode (block 504) is anoptional step. In various implementations, the device 100 mayautomatically adjust detection parameters in accordance with apredetermined relationship between the detection parameters and thepatient, environmental, and/or contextual inputs received from theexternal sensors. In some examples, rather than dynamically adjustingoperating characteristics based on the operating mode, the device 100may dynamically adjust its operating characteristics in response to thepatient, environmental, and/or contextual conditions.

In some implementations (e.g., implementations in which the selectedoperating mode is identified), one or more detection parameters thatcorrespond to the selected operating mode can be identified (block 506).Inputs received from the monitoring component (e.g., cardiac signalsreceived by the sensing electrodes 112) are then compared to the one ormore detection parameters as described above (block 508). Based on thecomparison, the wearable medical device 100 then determines whether thepatient may be experiencing a cardiac condition (block 510).

Determining whether the patient may be experiencing a cardiac condition(block 510) may include a verification step during which the wearablemedical device 100 determines whether the patient's cardiac signals arein fact indicative of a cardiac condition. In some implementations, acardiac condition may be erroneously identified due to the presence ofnoise in the cardiac signal (e.g., due to an electrode being partiallyremoved from the patient, due to environmental factors such as wet/humidconditions, etc.). The wearable medical device 100 may analyze a portionof the patient's cardiac signal (e.g., a 20 second ECG portion) anddetermine whether the cardiac signal represents a noise artifact. Thedetermination may be made according to a machine learning classifierbased approach. In some implementations, the cardiac signal is assigneda score, and the score is compared to one or more predetermined cardiacevent thresholds. Each cardiac event threshold may correspond to aparticular type of cardiac event. For example, one threshold maycorrespond to a ventricular tachycardia (VT) condition, and anotherthreshold may correspond to a ventricular fibrillation (VF) condition.

Still referring to FIG. 5, if it is determined that the patient is notexperiencing a cardiac condition, the wearable medical device 100 mayrestart the methodology at block 504. In some implementations (e.g.,implementations in which the selected operating mode is not identified),the wearable medical device 100 may restart the methodology at block506. The methodology may continuously step through blocks 504 through510 (or blocks 506 through 510) so long as a cardiac condition is notdetected. If it is determined that the patient may be experiencing acardiac condition, the wearable medical device selects a treatmentsequence based on the experienced cardiac condition (block 512). Theparticular treatment sequence may be tailored to the patient based onthe selected operating mode and the particular cardiac condition thatthe patient may be experiencing.

Performing a Treatment Sequence

FIG. 6 is a flow diagram 600 illustrating a methodology for performingthe selected treatment sequence (e.g., the treatment sequence selectedaccording to the methodology of FIG. 5). The methodology for performingthe selected treatment sequence may be initiated (block 602) after thetreatment sequence is selected by the wearable medical device 100. Insome implementations, the treatment sequence is automatically initiatedimmediately or substantially immediately after the treatment sequence isselected. Before delivering any therapy, the wearable medical device 100provides an indication that a therapy is about to be delivered to thepatient (block 604). The indication may be audio, visual, haptic, etc.After providing the indication, the wearable medical device 100 waitsfor an amount of time before delivering the therapy (block 606). In someexamples, the length of time (e.g., the length of the delay) can bebased on the selected operating mode. For example, the delay may beshorter when the wearable medical device 100 is operating in a defaultoperating mode than the delay that would be applied in a water or showeroperating mode. In some implementations, the amount of time isconfigurable (e.g., by a caregiver, the patient, another user, etc.) viaa user interface. For example, an initial configuration may be performedduring initial setup and/or baselining.

The length of the delay time before the treatment is delivered may bebased at least in part on the particular cardiac condition beingexperienced, the device operating mode, and/or the particular treatmentsequence selected. For example, if the wearable medical device 100determines that the patient may be experiencing a VT condition (e.g.,which may be prone to being misclassified), the patient may be afforded30 seconds to provide an input to stop the therapy from being delivered.In a water or shower operating mode, the patient may be afforded alonger delay (e.g., 45 seconds) to provide the input. However, if thewearable medical device 100 determines that the patient may beexperiencing a VF condition (which, e.g., may be more likely to beimmediately life-threatening as compared to a VT condition), the patientmay be afforded only 20 seconds to provide the input. In someimplementations, in a water or shower mode, the patient may be affordeda longer delay (e.g., 30 seconds) to provide the input.

During the delay time before the treatment is delivered, an input can bereceived that stops the therapy from being delivered (block 608). Forexample, the patient can interact with one or both of the responsebuttons (210 of FIG. 2) to cause the wearable medical device 100 torefrain from delivering the treatment. For example, the treatment may bea “false alarm,” such as an unnecessary and/or erroneous treatmentsuggestion.

In some examples, the input may take a different form depending on themode of the device. For example, one form of input may be a verbalcommand issued by the patient (e.g., a spoken phrase such as “STOPTREATMENT” or “SUSPEND TREATMENT”). In some implementation, the devicemay include voice recognition capability to verify that the patientprovided the command and not a bystander. Example methods and systemsfor using voice recognition to stop and/or suspend a treatment aredisclosed in issued U.S. Pat. No. 8,369,944, entitled “Wearabledefibrillator with audio input/output,” the contents of which areincorporated in their entirety herein. As noted, an ability to provide averbal command may be available in one or more special modes. Forexample, in a default mode, the patient may need to provide the inputvia the response buttons, but in an activity mode, the patient mayprovide the response via either the response buttons or as a verbalcommand. One or more other forms of input may be implemented in place ofor in addition to either the response buttons or verbal commands. Forexample, the input received (block 608) can be in the form of patientmotion information indicating that the patient is not unconscious. Thepatient motion information can be combined with other forms of input toconfirm the input and stop and/or suspend treatment.

In some implementations, receipt of the input can end the treatmentsequence (block 616). However, if no input is received, therapy (e.g., ashock such as a defibrillation shock or a pacing shock) is delivered tothe patient (block 610).

After the therapy is delivered, the wearable medical device 100 comparesinput received from the monitoring component to one or more detectionparameters (block 612). For example, input received from the monitoringcomponent can be compared to the same detection parameters describedabove with reference to block 508 of FIG. 5 for determining whether thepatient may be experiencing a cardiac condition. In someimplementations, the input received from the monitoring component can becompared to one or more other detection parameters. Based on thecomparison, the wearable medical device determines whether additionaltherapy is necessary (block 614). For example, if the input receivedfrom the monitoring component indicates that the patient is experiencingnormal heart function, the treatment sequence ends (block 616). On theother hand, if the input received from the monitoring componentindicates that the detected cardiac condition persists (or, e.g., that adifferent cardiac condition exists), the wearable medical device 100 maydetermine that additional therapy is necessary (block 614) and againprovide an indication that a therapy is about to be delivered to thepatient (block 604).

In some implementations, receipt of an input (block 608) onlytemporarily stops the therapy from being delivered to the patient, e.g.,rather than ending the treatment sequence altogether (block 616). Forexample, receipt of the input can stop the therapy from being delivered,but can cause the wearable medical device 100 to compare input receivedfrom the monitoring component to one or more detection parameters (block612) and determine, based on the comparison, whether additional therapy(e.g., additional to the declined therapy) is needed (block 614).

In some implementations, the device 100 can be configured toautomatically exit a special operating mode and return to a defaultoperating mode after an initial treatment has been delivered. As such,when the device 100 switches to the default operating mode, themonitoring and/or treatment parameters can be appropriately adjusted forsubsequent therapies. In some examples, the device 100 can be configuredto exit the special operating mode after the treatment sequence iscompleted and no further shocks are needed for the patient (e.g., afterrestoration of normal rhythm). In some implementations, the device 100can be configured to exit the special operating mode only after theentire treatment sequence is completed.

In some implementations, multiple indications are provided to thepatient before a treatment is delivered as described above. The multipleindications may be in various forms. For example, one or moreindications may be haptic, and one or more indications may be audible.In some implementations, a first indication is a haptic indication thatis intended to attract the patient's attention without disturbingothers. In the absence of a response from the patient, the wearablemedical device 100 may provide a second indication in the form of alow-volume audible alarm. The second indication may also be intended toattract the patient's attention without causing excessive disturbance toothers. If the patient does not respond to the second indication, thewearable medical device 100 may provide a third indication in the formof a loud-volume audible alarm. The third indication may be intended toattract the patient's attention irrespective of whether it may disturbothers. In some implementations, the third indication may be intended toattract the attention of others. As described below, the length of timethat is afforded to the patient to provide an input may vary accordingto the mode that the wearable medical device 100 is operating under atthe time. Similarly, the lengths and/or number and/or types ofindications provided may vary accordingly. For example, in one or morespecial operating modes, the device 100 may skip the haptic and/orlow-volume audible alarms and proceed directly to providing aloud-volume audible alarm. In one or more special operating modes, thedevice may shorten a duration of a first indication (e.g., haptic alarm)but lengthen durations of one or both of the second indication (e.g., alow-volume alarm) and the third indication (e.g., a loud-volume alarm).

In some implementations, if the wearable medical device 100 initiallydetermines that the patient may be experiencing a cardiac condition butsubsequently determines that the supposed cardiac condition is due to anoise artifact in the cardiac signal, the wearable medical device 100may be configured to modify the treatment sequence. For example, in someimplementations, if a noise artifact is detected in the cardiac signal,the wearable medical device 100 may suspend the treatment sequencemethodology for a period of time and refrain from providing anyindication to the patient. This is sometimes referred to as a silentnoise state, which can provide the wearable medical device 100 anopportunity to resolve the erroneous cardiac condition without userinteraction. The length of the suspension may be based at least in parton the particular cardiac condition that is supposedly being detectedand an operating mode of the device. For example, if the device is in aspecial operating mode (e.g., water or shower mode or an activity mode),then the length of suspension may be longer than the length ofsuspension in a default operating mode. For example, if the silent noisestate is configured to last about 30 seconds in a default operatingmode, the silent noise state can be configured to last about 45 secondsin a special operating mode. The silent noise period can be userconfigured for each of the default and special operating modes dependingon the caregiver and/or patient's preferences. For example, theconfiguration may be performed in a context of an initial setup and/orbaselining and/or patient fitting.

Following the treatment methodology suspension, if the wearable medicaldevice 100 is unable to resolve the erroneous cardiac condition, thewearable medical device 100 may provide an indication that a therapy isabout to be delivered. This is sometimes referred to as the noise alarmstate, during which the treatment sequence methodology continues to run.If the patient provides an input, the wearable medical device 100 mayextend the length of the noise alarm state for a period of time. Theextended length of time may be based at least in part on the particularcardiac condition that is supposedly being detected. In someimplementations, the patient can provide an indefinite number of inputsto indefinitely extend the noise alarm state.

Special Medical Device Operating Modes

As described above, the wearable medical device 100 can operate in adefault operating mode and one or more of a plurality of specialoperating modes. For example, the wearable medical device 100 canoperate in a water mode (sometimes referred to as a shower mode), apatient sleep mode, and/or an activity mode, among others. The operatingmode that the wearable medical device 100 is in can substantiallyinfluence its detection, alarms/alerts, and treatment sequences asdescribed above.

Water Operating Mode

FIG. 7A shows an example of the wearable medical device 100 being usedin the shower. In this example, the wearable medical device 100 is inwater mode (e.g., shower mode). The wearable medical device 100 includesa moisture sensor 702 that is configured to provide signals indicativeof an environmental humidity to the processor 318. The wearable medicaldevice 100 also includes an audio interface component 704 that caninclude one or both of a speaker and a microphone, the functions ofwhich are described in more detail below.

Selecting the Water Operating Mode

The wearable medical device 100 may have entered the water mode based ona methodology illustrated in a flow diagram 710 of FIG. 7B. Themethodology for selecting an operating mode is initiated (block 712)(e.g., automatically or in response to a triggering event). For example,the methodology for selecting an operating mode may be continuouslyrunning, or the methodology may initiate upon receiving an input from auser. The wearable medical device 100 is configured to monitor one ormore environmental conditions, including a humidity of an environment ofthe wearable medical device 100 (block 714). For example, the moisturesensor 702 can provide signals to the processor 318 indicative of theenvironmental humidity. The wearable medical device 100 then determineswhether the humidity meets or exceeds a threshold (e.g., a predeterminedthreshold). If the humidity does not meet nor exceed the threshold, thewearable medical device 100 may continue to monitor the humidity (block714). The monitoring may continue indefinitely or for a fixed period oftime (e.g., in the order of minutes, hours, or even longer). In someimplementations, the wearable medical device 100 may continue to monitorother environmental conditions to determine whether a differentoperation mode (e.g., other than the water mode) should be selected. Ifthe humidity meets or exceeds the threshold, the water operating mode isselected 720.

In some examples, a microphone can be employed instead of or in additionto the moisture sensor 702. The microphone can be configured to detectthe sound of falling water. Signals from such a microphone can be usedto correlate and/or confirm the information from the moisture sensor702.

In some implementations, the water operating mode can be selected basedon an input received by the wearable medical device 100 from a user(block 718). For example, a user can manually cause the wearable medicaldevice 100 to enter a particular mode using one or more inputmechanisms, such as the touch screen 220 and/or a button on the medicaldevice controller 120 and/or input mechanisms on other components of thewearable medical device (e.g., the user interface pod 140).

Selecting a Treatment Sequence in the Water Operating Mode

While in the water operating mode, the wearable medical device 100 canmonitor the cardiac signals received by the sensing electrodes 112 anddetermine whether the patient may be experiencing a cardiac conditionthat may require treatment based on modified detection parameters. Asnoted, the particular detection conditions that are used to determinewhether a cardiac condition is present may be based at least in part onthe water operating mode. For example, FIG. 7C is a flow diagram 730that illustrates a methodology performed by the wearable medical device100 to select a treatment sequence. The methodology for selecting atreatment sequence may be initiated (block 732) automatically. In otherwords, the wearable medical device may continuously monitor the cardiacsignals to determine whether a cardiac condition exists. The wearablemedical device 100 then identifies the selected operating mode (block734), which in this example is the water operating mode.

As mentioned above, the detection parameters (e.g., conditions) foridentifying a cardiac condition in a special operating mode may bedifferent than those used in the default operating mode. Once it isdetermined that the water operating mode is currently selected, thewearable medical device 100 determines modified thresholds for detectingwhether a cardiac condition exists in the patient (block 736).

As noted above, the modified thresholds for the special operating modecan be preset during an initial fitting and/or baselining state. In someexamples, the modified thresholds for the special operating mode can bepreset before the device is shipped to the patient servicerepresentative or caregiver for fitting on a patient.

For example, the modified thresholds for the water mode can include oneor more of modified phase detection parameters, modified magnitudedetection parameters, and/or modified noise detection parameters (e.g.,an ECG score and/or an amount of time for the device to declare a VT/VFevent, as described above). For example, for the water mode, themodified ECG score threshold can be set to 12. For example, the modifiedparameters can include modified thresholds that if met of transgressedcan cause the device to take action as described herein.

The modified thresholds correspond to the water operating mode and mayhave the effect of reducing the sensitivity of the wearable medicaldevice 100. While in the shower or taking a bath, a patient may lift orcause excessive movement of the ECG sensors. The excessive motion of thepatient and/or the sensors can cause noise artifacts that are sometimessignificant. In some examples, the noise artifacts can result in falsealerts and/or alarms that can be annoying or concerning to the patient.Thus, in the water mode, the device can be configured to ride throughthe noisy events. The patient's cardiac information that is receivedfrom the monitoring component is compared to the modified thresholds(block 738) as described in detail above. In some implementations, onlyone parameter is modified in the water mode relative to the defaultmode. In some implementations, one or more of phase detectionparameters, magnitude detection parameters, and/or noise detectionparameters can be modified. For example, in the water mode, the cardiacdetection analyzer may use one or more modified phase detectionparameters and modified magnitude detection parameters. Further, in someexamples, the noise detection module can compare an ECG score derived asdescribed above to a modified ECG score threshold.

The wearable medical device 100 then determines whether the patient maybe experiencing a cardiac condition by determining whether data relatedto the patient cardiac information meets or transgresses the modifiedthresholds (block 740). For example, continuing the example above, acardiac condition may exist if the methodology, using the modified phaseand magnitude detection parameters, determines that an incoming ECGsignal does not match baseline ECG measurements within a predeterminedperiod of time. Further, the noise detection methodology described abovecan confirm the cardiac condition on the basis of the modified ECG scorethreshold.

If the methodology determines that the patient may be experiencing acardiac condition, an appropriate treatment sequence is selected basedon the particular cardiac condition (block 742). However, if it isdetermined that the patient is not experiencing a cardiac condition, themethodology may revert to identifying the selected operating mode (block734) (e.g., in case it has changed since the previous identification)and proceed according to the methodology shown.

In some implementations, the wearable medical device 100 can beinstructed to refrain from selecting a treatment sequence. For example,the wearable medical device 100 can be configured to receive an inputfrom the patient that instructs the medical device to refrain fromselecting a treatment sequence (block 744). The input may be provided inresponse to an indication that treatment sequence selection has beeninitiated. In response to the input, the wearable medical device 100 mayrefrain from selecting a treatment sequence for a period of time (block746), in some examples acting as a snooze function. The period of timemay be based on the particular input received. The period of time can beindefinite or fixed (e.g., in the order of minutes, hours, or evenlonger). Following the period of time, the methodology may proceed toidentifying the selected operating mode (block 734) and proceedaccording to the methodology shown.

Performing a Treatment Sequence in the Water Operating Mode

FIG. 7D is a flow diagram 750 illustrating a methodology for performingthe selected treatment sequence (e.g., the treatment sequence selectedaccording to the methodology of FIG. 7C). After the methodology isinitiated (block 752), the wearable medical device 100 may provide anindication that a therapy is about to be delivered to the patient (block754). The indication may be based on the operating mode that thewearable medical device 100 is operating under at the time (in thisexample, the water mode). As mentioned above, the water mode may beselected when the patient is in the shower. Because showers produce ahigh volume of noise, the indication can be in the form of an alarm(e.g., that is emitted by a speaker of the audio interface component 704of FIG. 7A) having a sufficient volume such that it can be heard by thepatient. In some implementations, the wearable medical device 100includes a microphone for receiving an audio input. The volume of thealarm can be determined based on a magnitude of noise of the audioinput. Before delivering the therapy, the wearable medical device waitsfor a length of time during which an input can be received that stopsthe therapy from being delivered (block 756). The length of time and/orthe particular way that the input can be received can be tailored to thewater operating mode. For example, because a patient who is showeringmay be preoccupied, or because false alarms in water mode may beprevalent (e.g., due to the patient temporarily removing one or more ofthe electrodes), the length of time may be longer than a default lengthof time to allow the patient a sufficient opportunity to stop anunnecessary treatment from being delivered. Similarly, additional typesof inputs can be accepted by the wearable medical device 100 when it isin water mode to assist the user. For example, the microphone can beconfigured to receive an audio input from the user. In some examples, aportion of the wearable medical device 100 may remain outside of theshower, making it difficult for the patient to provide a tactile input(e.g., press one or both of the response buttons 210). Thus,configurations that allow for audio input can make it easier for thepatient to stop the treatment from being delivered.

During the length of time, the methodology determines whether an inputis received (block 758). If an input is received, the treatment sequencemay end (block 766). However, if no input is received, the therapy isdelivered to the patient (block 760). After the therapy is delivered,the wearable medical device 100 compares input received from themonitoring component to one or more detection parameters (block 762).For example, input received from the monitoring component (e.g., patientcardiac signals) can be compared to the threshold described above withreference to block 738 of FIG. 7C for determining whether the patientmay be experiencing a cardiac condition. In some implementations, theinput received from the monitoring component can be compared to one ormore other detection parameters.

Based on the comparison, the wearable medical device determines whetheradditional therapy is necessary (block 764). For example, if the inputreceived from the monitoring component indicates that the patient isexperiencing normal heart function, the treatment sequence ends (block766). On the other hand, if the input received from the monitoringcomponent indicates that the detected cardiac condition persists (or,e.g., that a different cardiac condition exists), the wearable medicaldevice 100 may determine that additional therapy is necessary and againprovide a loud audible alarm indicating that a therapy is about to bedelivered to the patient (block 754).

In some implementations, receipt of an input (block 758) onlytemporarily stops the therapy from being delivered to the patient (e.g.,rather than ending the treatment sequence altogether (block 766)). Forexample, receipt of the input can stop the therapy from being delivered,but can cause the wearable medical device 100 to compare input receivedfrom the monitoring component to one or more detection parameters (block762) and determine, based on the comparison, whether additional therapy(e.g., additional to the declined therapy) is needed (block 764).

Patient Sleep Operating Mode

FIG. 8 shows an example of the wearable medical device 100 being usedwhile the patient is sleeping. In this example, the device 100 is in apatient sleep operating mode. The wearable medical device 100 includes apressure sensor 802 (e.g., a strain gauge) that is configured to providesignals indicative of a degree of pressure to the processor 318, and amotion sensor 806 that is configured to provide signals indicative of adegree of motion to the processor 318. The wearable medical device 100also includes a vibration motor 804.

Selecting the Patient Sleep Operating Mode

The wearable medical device 100 may have entered the patient sleepoperating mode based on a methodology similar to that described abovewith reference to FIG. 4B. For example, the patient may provide an inputto manually enter the device into the patient sleep operating mode (seestep 418 of FIG. 4B).

In some examples, the wearable medical device 100 is configured tomonitor one or more environmental conditions. For example, theenvironmental conditions include a degree of pressure and a degree ofmotion experienced by the wearable medical device 100.

The pressure sensor 802 (e.g., which can be incorporated on a posteriorof the garment 110) can include a strain gauge that includes a strainsensitive metal foil pattern. When pressure is applied to certainportions of the wearable medical device 100, the metal foil deforms. Thedeformation causes the overall length of the metal foil pattern tochange. The physical change in the metal foil pattern causes theend-to-end electrical resistance of the pattern to change. An outputvoltage across terminals of the metal foil pattern corresponds to thechange of resistance, and therefore is indicative of an amount of strainmeasured by the strain gauge. The pressure sensor 802 can provideinformation related to the amount of strain to the processor 318, andthe processor 318 can determine whether the amount of strain meets orexceeds a predetermined threshold. The threshold may be indicative of adegree of pressure typically experienced when the patient is sitting orlying down.

The motion sensor 806 can include one or more accelerometers,gyroscopes, or other kinds of sensors that are configured to measuremotion and/or orientation information and provide such information tothe processor 318. The processor can determine whether the motion and/ororientation information is below a predetermined threshold. Thethreshold may be indicative of a degree of motion typically experiencedwhen the patient is in a non-sleep state.

The wearable medical device 100 can consider one or both of the pressureinformation and the motion information to determine whether the patientsleep operating mode should be selected. For example, if the strainthreshold is met or exceeded and/or the motion information is below thethreshold, the wearable medical device 100 may infer that the patient islying down and/or sitting down, and may enter the patient sleepoperating mode accordingly. In some implementations, a user who issitting or lying down is not necessarily asleep. Thus, in someimplementations, the wearable medical device 100 can consider otherinformation instead of or in addition to the pressure and motioninformation to determine whether the patient sleep operating mode shouldbe selected. For example, the wearable medical device 100 may considerinput (e.g., patient cardiac signals) received from the monitoringcomponent and/or other patient health metrics (e.g., a heart rate belowa threshold) to determine whether the patient is exhibiting a conditiontypically associated with sleep.

Selecting a Treatment Sequence in the Patient Sleep Operating Mode

The methodology for selecting a treatment sequence when the wearablemedical device 100 is in the patient sleep operating mode may be similarto the methodology described above with reference to FIG. 5. Theparticular conditions that are used to determine whether the patient maybe experiencing a cardiac condition may be based at least in part on thedefault operating mode.

In some examples, a patient who is sleeping may exhibit differentcardiac signals than those typically exhibited while awake. Thus, theconditions for determining whether a cardiac condition exists may bedifferent when the patient is sleeping. For example, the wearablemedical device 100 may implement a lessened threshold for detectingwhether a cardiac condition exists, thereby having the effect ofincreasing the sensitivity of the wearable medical device 100.

In some implementations, the wearable medical device 100 may beconfigured to detect other medical conditions of the patient (e.g., inaddition to cardiac conditions) based on the operating mode. Forexample, while in the patient sleep operating mode, the wearable medicaldevice 100 may be configured to initiate its ability to detect sleepapnea in the patient. Indicators of sleep apnea may be related totransthoracic impedance, respiration rate, heart rate, certain pulmonaryand/or heart sounds, and pulse oximetry, among others. The wearablemedical device 100 can include one or more sensors configured to monitorone or more of these indicators to determine whether the patient isexperiencing sleep apnea. In some implementations, the wearable medicaldevice 100 is configured to alert the patient (e.g., with an audibleand/or haptic alarm) if sleep apnea is detected. In some implementation,the detection of sleep apnea may indicate that the patient isexperiencing a cardiac condition. Thus, in some implementations, apatient who is experiencing symptoms of sleep apnea, but who is notexhibiting other specific signs of a cardiac condition, may be treatedas potentially experiencing a cardiac condition. In someimplementations, the wearable medical device 100 may be configured toproceed with selecting a treatment sequence based on characteristics ofthe sleep apnea.

Performing a Treatment Sequence in the Patient Sleep Operating Mode

The methodology for performing a treatment sequence when the wearablemedical device 100 is in the patient sleep operating mode may be similarto the methodology described above with reference to FIG. 6. The way bywhich the wearable medical device 100 provides an indication that atherapy is about to be delivered may be based at least in part on thepatient sleep operating mode. For example, the indication can be ahaptic indication provided by the vibration motor 804 so as not to alarmthe patient and/or disturb other individuals who are sleeping in thevicinity of the patient. In some examples, the indication can be anaudible alarm provided by a speaker that is intended to awaken thepatient. In some examples, the intensity of the indication (e.g., thevibration intensity, the volume, etc.) can be adjustable such that thepatient can define an intensity that is sufficient to awaken him or her.

The way by which the patient can provide an input to stop the therapyfrom being delivered may be based at least in part on the patient sleepoperating mode. The patient may be in a disoriented state upon awakeningin response to the indication. The wearable medical device 100 may beconfigured to receive inputs other than tactile inputs (e.g., pressingone or both of the response buttons 210), such as an audio input thatcan be received by a microphone, thereby allowing the patient to moreeasily stop the therapy from being delivered.

The length of time afforded to the patient to provide the input may bebased at least in part on the patient sleep operating mode. The patientmay have trouble waking up, or may be in a disoriented state uponawakening in response to the indication. The treatment sequence may beadjusted such that the patient is afforded more time to provide an inputthan the amount of time afforded in the default operating mode. Forexample, the patient may be afforded 45 seconds to provide an inputbefore the therapy is delivered.

Activity Operating Mode

FIG. 9 shows an example of the wearable medical device 100 being usedwhile the patient is active. In this example, the device is in anactivity operating mode. The wearable medical device 100 includes amotion sensor 902 that is configured to provide signals indicative of adegree of motion to the processor 318. The motion sensor 902 can includeone or more accelerometers and/or gyroscopes that are configured tomeasure motion and/or orientation information.

Selecting the Activity Operating Mode

The wearable medical device 100 may have entered the activity operatingmode based on a methodology similar to that described above withreference to FIG. 4B. For example, the patient may provide input toplace the device 100 in the activity operating mode (see step 418 ofFIG. 4B). In some implementations, the wearable medical device 100 isconfigured to monitor one or more environmental conditions. In someimplementations, the environmental conditions include a degree of motionexperienced by the wearable medical device 100. The motion sensor 806can include one or more accelerometers and/or gyroscopes that areconfigured to measure motion and/or orientation information and providesuch information to the processor 318. The processor 318 can determinewhether the motion and/or orientation information is above apredetermined threshold. The threshold may be indicative of a degree ofmotion typically experienced when the patient is in an active state.

The wearable medical device 100 can consider the motion information todetermine whether the activity operating mode should be selected. Forexample, if the motion threshold is met or exceeded, the wearablemedical device 100 may infer that the patient is in an active state, andmay enter the activity operating mode accordingly. In someimplementations, the wearable medical device 100 can consider otherinformation instead of or in addition to the motion information todetermine whether the activity operating mode should be selected. Forexample, the wearable medical device 100 may consider input (e.g.,patient cardiac signals) received from the monitoring component and/orother patient health metrics (e.g., a heart rate and/or a respiratoryrate above a threshold) to determine whether the patient is exhibiting acondition typically associated with activity.

Selecting a Treatment Sequence in the Activity Operating Mode

The methodology for selecting a treatment sequence when the wearablemedical device 100 is in the activity operating mode may be similar tothe methodology described above with reference to FIG. 5. The particularconditions that are used to determine whether the patient may beexperiencing a cardiac condition may be based at least in part on theactivity operating mode and may be adjusted relative to defaultconditions. In some cases, a patient who is active may exhibit differentcardiac signals than those typically exhibited while inactive. Thus, theconditions for determining whether a cardiac condition exists may bedifferent when the patient is active (e.g., playing a sport).

The modified thresholds correspond to the activity operating mode andmay have the effect of reducing the sensitivity of the wearable medicaldevice 100. While playing a sport and/or running and/or otherwise beingactive, a patient may unintentional lift or cause excessive movement ofthe ECG sensors. The excessive motion of the patient and/or the sensorscan cause noise artifacts that are sometimes significant. In someexamples, the noise artifacts can result in false alerts and/or alarmsthat can be annoying or concerning to the patient. Thus, in the activitymode, the device can be configured to ride through the noisy events. Thepatient's cardiac information that is received from the monitoringcomponent is compared to the modified thresholds (block 738) asdescribed in detail above.

In some implementations, only one parameter is modified in the activitymode relative to the default mode. In some implementations, one or moreof phase detection parameters, magnitude detection parameters, and/ornoise detection parameters can be modified. For example, in the activitymode, the cardiac detection analyzer may use one or more modified phasedetection parameters and modified magnitude detection parameters.Further, in some examples, the noise detection module can compare an ECGscore derived as described above to a modified ECG score threshold.

Performing a Treatment Sequence in the Activity Operating Mode

The methodology for performing a treatment sequence when the wearablemedical device 100 is in the activity operating mode may be similar tothe methodology described above with reference to FIG. 6. The way bywhich the wearable medical device 100 provides an indication that atherapy is about to be delivered may be based at least in part on theactivity operating mode. For example, after the treatment methodology isinitiated, the wearable medical device 100 may provide an indicationthat a therapy is about to be delivered to the patient. The indicationmay be based on the activity operating mode that the wearable medicaldevice 100 is operating under.

As mentioned above, the activity mode may be selected when the patientis in the performing a sport or other physical activity. Because suchactivities can produce a high volume of audible noise, the indicationcan be in the form of an alarm (e.g., that is emitted by a speaker ofthe audio interface component 704 of FIG. 7A) having a sufficient volumesuch that it can be heard by the patient. In some implementations, thewearable medical device 100 includes a microphone for receiving audioinput. The volume of the alarm can be determined based on a magnitude ofnoise of the audio input. Before delivering the therapy, the wearablemedical device waits for a length of time during which an input can bereceived that stops the therapy from being delivered. The length of timeand/or the particular way that the input can be received can be tailoredto the activity operating mode. For example, because a patient who isperforming an activity may be preoccupied, or because false alarms inactivity mode may be prevalent (e.g., due to the patient temporarilyremoving one or more of the electrodes), the length of time may belonger than a default length of time to allow the patient a sufficientopportunity to stop an unnecessary treatment from being delivered.

The way by which the patient can provide an input to stop the therapyfrom being delivered may be based at least in part on the activityoperating mode. For example, the ability of the patient to suspend atreatment via a spoken command may be initiated in the activity mode. Assuch, additional types of inputs can be accepted by the wearable medicaldevice 100 when it is in activity mode to assist the user. For example,the microphone can be configured to receive an audio input from theuser. In some examples, it may be difficult for the patient to provide atactile input (e.g., by pressing one or both of the response buttons210) while the patient is performing a physical activity. Thus,configurations that allow for audio input can make it easier for thepatient to stop the treatment from being delivered. If an input isreceived, the treatment sequence may be suspended. However, if no inputis received, the therapy is delivered to the patient.

The length of time afforded to the patient to provide the input may bebased at least in part on the activity operating mode. In someimplementations, the patient may be preoccupied or distracted in theactive state. The treatment sequence may be adjusted such that thepatient is afforded more time to provide an input than the amount oftime afforded in the default operating mode. For example, the patientmay be afforded 45 seconds to provide an input before the therapy isdelivered. However, in some implementations, the patient may be moresusceptible to a cardiac condition while in the active state. Forexample, an elderly patient or a patient with a particular cardiachealth history may be at risk when he or she is active. The treatmentsequence may be adjusted such that potentially life threatening cardiacconditions are treated without excessive delay. For example, the patientmay be afforded less time to provide an input than the amount of timeafforded in the default operating mode. For example, the patient may beafforded 20 seconds to provide an input before the therapy is delivered.

Medical Device Learning

In some implementations, the wearable medical device 100 is configuredto acquire data related to its pattern of use, including locationsvisited, conditions experienced, treatments applied, and situationsencountered, among others. The wearable medical device 100 can use suchpattern of use data to learn how the wearable medical device 100 hasbeen used in the past, and to assist in setting operational parametersfor future uses. In some implementations, the pattern of use data canassist in selecting an operating mode and selecting and/or performing atreatment sequence. The data related to the pattern of use may beacquired automatically (e.g., during the first day or week of use by thepatient) or manually (e.g., in response to input received by the user).

Selecting the Operating Mode

In some implementations, the wearable medical device 100 includes alocation module that is configured to measure the location of themedical device. The location module may be one or more of a GPS module,an NFC module, a Bluetooth® module, a WLAN module, or one or more indoorpositioning systems (IPS) that are configured to provide a signal to theprocessor 318 indicative of the location of the patient outfitted withthe wearable medical device 100. The location may be in the form of GPScoordinates or some other coordinate system (e.g., coordinatesassociated with an indoor positioning system). In some implementations,the location is correlated with additional information to determinecharacteristics of the location. For example, the location may becorrelated with a database (e.g., a mapping database) to determine thata particular location corresponds to a restaurant, a gym, an athleticfacility, a park, a hotel, etc. The characteristics of the location canassist in automatic operating mode selection. For example, the wearablemedical device 100 may enter the activity operating mode when thepatient is at a location that corresponds to a gym or an athleticfacility.

The wearable medical device 100 can identify its location when it is ina particular operating mode. Over time, the wearable medical device 100can correlate particular locations with particular operating modes. Forexample, the wearable medical device 100 may recognize that it operatesin patient sleep operating mode whenever it is at a location associatedwith the patient's bedroom. Once the correlation is sufficientlyestablished, the wearable medical device 100 may automatically enterpatient sleep operating mode when the patient is in that bedroom. Insome implementations, the wearable medical device 100 may wait for aparticular period of time before automatically entering the particularoperating mode. For example, continuing with the previous example, thewearable medical device 100 may wait five minutes after the patiententers the bedroom before entering the patient sleep operating mode toaccount for situations in which the patient is briefly in the bedroomfor non-sleep reasons.

In some implementations, the wearable medical device 100 can identifypatterns of use unrelated to the location of the device to assist inoperating mode selection. For example, the wearable medical device 100may identify that it typically enters the water operating mode onweekdays at 7:00 AM. If a correlation between the operating mode andsuch patterns is sufficiently established, the wearable medical device100 may automatically enter the water operating mode at times that fitwithin the established pattern. In some implementations, rather thanautomatically entering the particular operating mode, the wearablemedical device may “expect” to enter the operating mode, and thus mayrelax threshold conditions for entering the operating mode duringparticular time periods.

In some implementations, the patient can manually enter informationrelated to operating mode correlations into the wearable medical device100. For example, when the patient is at the gym, he or she may instructthe wearable medical device 100 to automatically enter activityoperating mode whenever the patient is at the location associated withthe gym. The instruction may be provided using a pulldown menu or someother configuration presented by a user interface (e.g., the touchscreen 220) or input mechanism.

Selecting/Performing a Treatment Sequence

Pattern of use data can also be used to assist in selecting and/orperforming a treatment sequence. As described above, the wearablemedical device 100 is configured to compare patient information todetection parameters to determine whether the patient is experiencing acardiac condition, select a treatment sequence based on the experiencedcardiac condition, and provide the treatment sequence. The patient canstop the treatment from being delivered by providing an input to thewearable medical device 100. In some implementations, the wearablemedical device 100 can store information related to such overriddentreatments to better refine the detection parameters. For example, ifthe patient always refuses a treatment that is suggested based on aparticular detection parameter, a threshold related to that detectionparameter may be heightened or lowered accordingly (e.g., to reduce thesensitivity of the wearable medical device with respect to the detectionparameter).

Alternative Implementations

While certain implementations have been described, other implementationsare possible.

While the medical device has been described as being configured tooperate in a default mode and various special operating modes (e.g.,water mode, patient sleep mode, activity mode), in some implementations,the medical device is configured to operate in additional modes. Theadditional modes can include an acrobatic operating mode for when thepatient is performing acrobatics and/or a physical intimacy operatingmode for when the patient is engaging in physical intimacy. In someimplementations the acrobatic operating mode and the physical intimacyoperating mode can follow a methodology similar to that described withreference to the activity operating mode. A patient engaging inacrobatics and/or physical intimacy may exhibit different cardiacsignals than those typically exhibited while inactive. Thus, in someimplementations, the acrobatic operating mode and/or the physicalintimacy mode may cause the medical device to implement modifiedthresholds for detecting whether a cardiac condition exists in thepatient, thereby having the effect of decreasing the sensitivity of themedical device. The amount of time afforded to the patient to provide aninput to stop the therapy from being delivered may also be adjusted inthese modes (e.g., the amount of time may be increased, or in someimplementations, decreased).

The plurality of operating modes can each include additional featuresbeyond those described above. Such additional features are sometimesreferred to herein as sub-modes. The sub-modes can include noisy mode,home mode, motor vehicle mode, car mode, motorcycle mode, physicalimpairment mode, and muffled mode. Like the special modes describedabove, the sub-modes may cause the medical device to adjust itsmethodology for selecting a treatment sequence and/or adjust itsmethodology for performing the treatment sequence. For example, themedical device may enter noisy mode if it detects ambient noise of amagnitude beyond a threshold, and the treatment sequence may be modifiedsuch that a haptic indication is provided for notifying the patient thata treatment is about to be delivered. Alternatively, the indication maybe an audible alert that is sufficient in volume to be heard over theambient noise. In some implementations, the medical device may enter amotor vehicle mode (e.g., a car mode and/or a motorcycle mode) in whichan audio interface of the medical device is configured to receive andprovide audible information. The audio interface can be configured tointeract with a car audio system.

In some implementations, the medical device can be configured to adjustits user interface arrangement and/or its method of reportinginformation based on a sub-mode. For example, in some implementations,the sub-modes can include medical facility mode, tech support mode,paramedic/EMS mode, and pediatric mode.

For example, in medical facility mode, the medical device may providetwo types of information: basic information that is provided to thepatient, and complex information that is provided to a caregiver.

In paramedic/EMS mode, the medical device may provide information to aparamedic and/or allow the paramedic to control at least some aspects ofthe medical device. For example, in paramedic/EMS mode, a paramedic maybe able to adjust treatment parameters for determining whether thepatient may be experiencing a medical condition. In someimplementations, the paramedic/EMS mode may be entered in response tothe medical device detecting a noise signature of an ambulance siren.

In pediatric mode, the medical device may provide alerts in a style thatis tailored towards kids (e.g., displaying cartoons on the device) andconcurrently provide more detailed alerts to another entity (e.g., aparent).

In tech support mode, the medical device may be configured to providetroubleshooting information related to the medical device to a technicaluser. In some implementation, one or more of these sub-modes can alsocause the medical device to adjust the treatment sequence and/or thedetection parameters for determining whether the patient is experiencinga cardiac event.

One or more parameters corresponding to these modes can be adjusted(e.g., during initial patient fitting and/or baselining).

As described above, the medical device determines whether the patientmay be experiencing a cardiac condition based on one or more detectionparameters (e.g., conditions), and such detection parameters may dependon the mode that the medical device is operating under at the time. Oneexample of a detection parameter that is described above is related tothe power spectral density (PSD) of a cardiac signal (e.g., an ECGsignal). However, other detection parameters can be used instead of orin addition to the PSD. For example, one or more of the detectionparameters can be related to other components of the patient's ECGsignal, such as waveform shape variations (e.g., QRS shape), durationvariations (e.g., QRS or T-wave width, ST segment width), amplitudevariations (e.g., R wave or T-wave amplitude), period variations (e.g.,R-R interval, QT interval, ST interval), T wave alternans (TWA), heartrate variability (HRV), heart rate turbulence (HRT), PR interval,slurring of the QRS complex, premature ventricular contraction (PVC),frequency analysis, a VT or VF template, QT variability, QT intervallength, and/or combinations and/or ratios of the aforementioned.

While we have described the medical device as being configured tomeasure location information using a location module, in someimplementations, location information is ascertained by one or moreother sensors. For example, in some implementations, the medical deviceincludes a microphone that can measure audio information and correlatethe audio information with a particular location.

While we have described a number of examples of how the medical devicemay enter the various operating modes, other implementations arepossible. In some implementations, the medical device may include amicrophone, and the medical device may be configured to enter anoperating mode based on received audio information. For example, if themedical device detects minimal noise (e.g., below a predeterminedthreshold) over a particular length of time, it may enter the patientsleep operating mode. In some implementations, one or more otherconditions may need to be satisfied for a particular operating mode tobe selected. For example, continuing with the previous example, themedical device may enter the sleep operation mode if it detects i)minimal noise, and ii) minimal motion.

While we have described a number of examples of how the treatmentsequence can be adjusted based on the operating mode, otherimplementations are possible. For example, the amount of time affordedto the patient for providing an input to stop the treatment from beingdelivered may be different than those described above. In someimplementations, the amount of time is user-configurable. For example,the amount of time may be set by the patient or another entity (e.g., acaregiver). In some implementations, the amount of time can bedetermined based on information stored in a database (e.g., a hospitaldatabase).

In some implementations, the medical device is configured to interactwith one or more other medical devices. While the medical devicesdescribed herein have been described as including a variety of sensors,in some implementations, one or more of the sensors may instead be partof a separate medical device. For example, in some implementations, themedical device is configured to interact with a blood pressure monitor,a respiration monitor, a pulse oximeter, and/or a medical device thatincludes a photoplethysmograph (PPG) sensor. In some implementations,the medical device is configured to interact with a medical device thatis configured to detect a heart rate condition in the patient. Themedical device for detecting a heart rate condition can provideinformation to the medical device, and the medical device can select atreatment sequence for correcting the particular heart rate condition(e.g., one or more pacing shocks).

Example Infrastructure

Software running on the medical device controller (e.g., controller 120of FIGS. 1-3A) can be realized by instructions that upon execution causeone or more processing devices to carry out the processes and functionsdescribed above, for example, selecting an operating mode, selecting atreatment sequence, and/or performing a treatment sequence, amongothers. The instructions can include, for example, interpretedinstructions such as script instructions, or executable code, or otherinstructions stored in a computer readable medium.

A server (e.g., the remote server 326 and 352 as shown in FIGS. 3A and3B) can be distributively implemented over a network, such as a serverfarm, or a set of widely distributed servers or can be implemented in asingle virtual device that includes multiple distributed devices thatoperate in coordination with one another. For example, one of thedevices can control the other devices, or the devices may operate undera set of coordinated rules or protocols, or the devices may becoordinated in another fashion. The coordinated operation of themultiple distributed devices presents the appearance of operating as asingle device.

In some examples, the components of the controller 120 may be containedwithin a single integrated circuit package. A system of this kind, inwhich both a processor (e.g., the processor 318) and one or more othercomponents (e.g., the operating condition analyzer 320, the cardiacevent detector 324, etc.) are contained within a single integratedcircuit package and/or fabricated as a single integrated circuit, issometimes called a microcontroller. In some implementations, theintegrated circuit package includes pins that correspond to input/outputports (e.g., that can be used to communicate signals to and from one ormore of the input/output interface devices).

Although an example processing system has been described above,implementations of the subject matter and the functional operationsdescribed above can be implemented in other types of digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Implementationsof the subject matter described in this specification, such as storing,maintaining, and displaying artifacts can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a tangible program carrier, for example acomputer-readable medium (e.g., the data storage 304), for execution by,or to control the operation of, a processing system. The computerreadable medium can be a machine readable storage device, a machinereadable storage substrate, a memory device, or a combination of one ormore of them.

The term “system” may encompass all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. A processing system caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them. Insome implementations, operating systems can include a Windows basedoperating system, OSX, or other operating systems. For instance, in someexamples, the processor may be configured to execute a real-timeoperating system (RTOS), such as RTLinux, or a non-real time operatingsystem, such as BSD or GNU/Linux.

A computer program (also known as a program, software, softwareapplication, script, executable logic, or code) can be written in anyform of programming language, including compiled or interpretedlanguages, or declarative or procedural languages, and can be deployedin any form, including as a standalone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

Computer readable media suitable for storing computer programinstructions and data include all forms of non-volatile or volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks ormagnetic tapes; magneto optical disks; and CD-ROM, DVD-ROM, and Blu-Raydisks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry. Sometimes a server(e.g., the remote server 326 and 352 as shown in FIGS. 3A and 3B) is ageneral purpose computer, and sometimes it is a custom-tailored specialpurpose electronic device, and sometimes it is a combination of thesethings. Implementations can include a back end component, e.g., a dataserver, or a middleware component, e.g., an application server, or afront end component, e.g., a client computer having a graphical userinterface or a Web browser through which a user can interact with animplementation of the subject matter described is this specification, orany combination of one or more such back end, middleware, or front endcomponents. The components of the system can be interconnected by anyform or medium of digital data communication, e.g., a communicationnetwork such as the connection between the remote server 326, 352 andthe network interface 306 shown in FIGS. 3A and 3B. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), e.g., the Internet.

Having described several aspects of at least one example of thisdisclosure, the examples of the methods and apparatuses discussed hereinare not limited in application to the details of construction and thearrangement of components set forth in this description or illustratedin the accompanying drawings. The methods and apparatuses are capable ofimplementation in other examples and of being practiced or of beingcarried out in various ways. Examples of specific implementations areprovided herein for illustrative purposes only and are not intended tobe limiting. In particular, acts, elements and features discussed inconnection with any one or more examples are not intended to be excludedfrom a similar role in any other examples. Accordingly, the foregoingdescription and drawings are by way of example only

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toexamples or elements or acts of the systems and methods herein referredto in the singular may also embrace examples including a plurality ofthese elements, and any references in plural to any example or elementor act herein may also embrace examples including only a single element.References in the singular or plural form are not intended to limit thepresently disclosed systems or methods, their components, acts, orelements. The use herein of “including,” “comprising,” “having,”“containing,” “involving,” and variations thereof is meant to encompassthe items listed thereafter and equivalents thereof as well asadditional items. References to “or” may be construed as inclusive sothat any terms described using “or” may indicate any of a single, morethan one, and all of the described terms.

What is claimed is:
 1. An ambulatory medical device comprising: one ormore monitoring components comprising at least one ECG electrode andassociated circuitry configured to detect a cardiac arrhythmia conditionof a patient; a sensor and associated circuitry configured to monitorone or more environmental conditions including at least one of moistureand motion; a plurality of therapy electrodes configured to deliver atreatment to the patient in response to a detected the cardiacarrhythmia condition; and at least one processor in communication withthe sensor and associated circuitry, the at least one ECG electrode andassociated circuitry, and the plurality of therapy electrodes, the atleast one processor configured to detect the one or more environmentalconditions based on input from the sensor, change a device operatingmode based on the one or more detected environmental conditions, adjustone or more detection thresholds for detecting the cardiac arrhythmiacondition of the patient based at least in part on the change in thedevice operating mode, prompt the patient to provide a confirmation ofthe change in the device operating mode before adjusting the one or moredetection thresholds, extend a delay period of a delivery of thetreatment based in part on the confirmation of the change in the deviceoperating mode, and deliver the treatment via the plurality of therapyelectrodes in response to detecting the cardiac arrhythmia condition ofthe patient based on the adjusted one or more detection thresholds ofthe changed device operating mode and not receiving an input from thepatient during the extended delay period.
 2. The ambulatory medicaldevice of claim 1, wherein the at least one processor is configured toadjust the one or more detection thresholds dynamically.
 3. Theambulatory medical device of claim 1, further comprising a locationmodule configured to determine the location of the ambulatory medicaldevice, wherein the location module is one of a GPS module, an NFCmodule, a Bluetooth® module, and a WLAN module.
 4. The ambulatorymedical device of claim 1, further comprising an audio interfaceconfigured to receive and provide audible information, wherein the atleast one processor is configured to further adjust the one or moredetection thresholds based at least in part on received audibleinformation.
 5. The ambulatory medical device of claim 4, wherein theaudio interface is configured to interact with an audio system thatreceives, provides, or receives and provides audible information.
 6. Theambulatory medical device of claim 1, wherein the plurality of therapyelectrodes is configured to deliver one or both of defibrillationcurrent and a pacing pulse.
 7. The ambulatory medical device of claim 1,wherein the at least one processor is further configured to detect thatthe cardiac arrhythmia condition may be occurring based at least in parton 1) input received from the one or more monitoring components and 2)one or more detection thresholds that correspond to the one or moreadjusted detection thresholds; and select a treatment sequencecorresponding to the cardiac arrhythmia condition.
 8. The ambulatorymedical device of claim 7, wherein the one or more monitoring componentsare configured to monitor one or more patient parameters, wherein theone or more patient parameters comprise one or more of a heart rate, arespiration rate, a blood pressure, and one or more occurrences ofpre-ventricle contraction (PVC).
 9. The ambulatory medical device ofclaim 1, wherein the adjusted one or more detection thresholds comprisea lower or higher sensitivity level for detecting the cardiac arrhythmiacondition than a sensitivity level of the one or more detectionthresholds prior to the adjusting.
 10. The ambulatory medical device ofclaim 1, further comprising a memory in communication with the at leastone processor, wherein the sensor comprises a moisture sensor configuredto detect an environmental moisture content, wherein the change in thedevice operating mode comprises a change in the device operating mode toa water operating mode, and wherein the at least one processor isconfigured to select the water operating mode of the device if themoisture sensor detects an environmental moisture content that meets orexceeds a threshold level of detected humidity stored in the memory. 11.The ambulatory medical device of claim 10, wherein the at least oneprocessor is configured to analyze an ECG signal from the at least oneECG electrode to compile an ECG score that is stored in the memory ofthe ambulatory medical device and compare the ECG score with a thresholdECG score that is stored in the memory and indicative of the cardiacarrhythmia condition, and wherein the at least one processor isconfigured to automatically adjust the threshold ECG score according toa predetermined relationship stored in the memory of the threshold ECGscore with a level of detected environmental moisture content.
 12. Theambulatory medical device of claim 1, wherein the sensor comprises amotion sensor configured to detect a motion indicative of the patientbeing in an active state, wherein the change in the device operatingmode comprises a change in the device operating mode to an activityoperating mode, and wherein the at least one processor is configured toselect the activity operating mode of the device if the motion sensordetects a motion indicative of the patient being in an active state. 13.The ambulatory medical device of claim 12, further comprising a memoryin communication with the at least one processor, the memory storing theone or more detection thresholds, wherein the one or more detectionthresholds comprises a threshold ECG score indicative of the cardiacarrhythmia condition, and wherein the at least one processor isconfigured to automatically adjust the threshold ECG score according toa predetermined relationship stored in the memory of the threshold ECGscore with a level of detected motion.